
Armed police have flooded London's streets as the terror threat level was raised to critical amid fears the Parsons Green bomber could strike again, Theresa May announced tonight.

The introduction of Operation Temperer will see soldiers replacing police at key sites including nuclear power plants to free up extra armed officers for regular patrols.

Scotland Yard said it is making 'excellent' progress in hunting the suspected terrorist who set off a crude bucket bomb on a packed commuter train by Parsons Green tube station in west London at 8.20am.

Mrs May said in a statement from Number 10: 'The Joint Terrorism Analysis Centre has now decided to raise the national threat level from severe to critical - this means their assessment is that a further attack may be imminent.'

Minutes later Assistant Commissioner Mark Rowley suggested there might have been more than one person involved, stating that police were 'chasing down suspects'.

Police identified the suspected terrorist using CCTV footage but the investigation has been overshadowed by an extraordinary diplomatic row triggered by Donald Trump

The US President tweeted just hours after the rush hour blast that police had the attacker 'in their sights' and should have been 'more proactive' in catching 'the loser'.

Scotland Yard hit back and said Mr Trump's comments were 'pure speculation' while senior officers refused to name the suspect.

The President later rowed back on his controversial comments by posting another tweet saying, ‘our hearts and prayers go out to the people of London’.

The Islamic State group claimed responsibility for the attack tonight, saying its 'soldiers' had 'planted IEDs'.

Scroll down for videos.

A photograph of the flaming white bucket taken just after it exploded around 8.20am shows a number of wires protruding out of the top and on to the train carriage floor

The majority of victims suffered 'flash burns' including to their heads (pictured) and several have been taken to a specialist burns unit

A victim, believed to be a schoolchild, is carried from the station with charred legs (left) as others were treated for burns in the street and neighbouring shops (centre) and an 11-year-old who was found on the floor asking for his brother

Theresa May gave a statement from within Downing Street in which she announced the terror threat level would be raised to critical, its highest level

Assistant Commissioner Mark Rowley suggested there may have been more than one person involved stating that police were 'chasing down suspects'

A well-dressed young woman was walked to safety by a Met officer after having her head bandaged after suffering a burn or wound to her cheek

Firefighters from the London Fire Brigade raced to the scene in west London and were there within five minutes

This photograph captured the moment the first members of the emergency services raced to the scene within five minutes of the explosion

Elite armed counter-terrorism police are at the scene amid reports of the suspect being on the run and claims of a second device

At least 20 people are believed to have been injured by the blast, many of whom suffered burns from the fireball that flew through the carriage (Peter Crowley pictured left today and right before the attack)

A traumatised and injured passenger on the ill-fated Parsons Green train is taken away by paramedics and firefighters

The majority of the victims have suffered 'flash burns' caused by the ignition - but it appears that the bomb did not properly detonate

A forensic officer outside Parsons Green station in West London where there remains a heavy police presence as the manhunt for the suspected terrorist continues

Security was stepped up at stations around London following this morning's attack. Pictured is a British Transport Police officers at Euston

A police officer watches on as commuters file into the underground at Euston Station amid newly tightened security

As Britain faced its fifth terror attack in a year it has emerged:

Bucket bomb left on Tube train - which had a timer - failed to explode properly at 8.20am but left 29 injured;

Most victims suffered 'flash burns' and others crush injuries in 'human stampede' as people fled the train;

Two hours after the explosion Metropolitan Police confirmed they were treating it as a terrorist incident;

The IED used Christmas lights as a fuse, as recommended by ISIS magazines and online bomb manuals;

Police are looking for multiple suspects - and officers have told MailOnline that main suspect is armed;

Donald Trump insists he has been briefed on bombing and Scotland Yard knew of the suspect before attack;

The Metropolitan Police hit back at 'pure speculation' and refused to name the suspect they are looking for;

Met spotters are watching back CCTV from the train and at Tube stations to trace the bomber's steps;

ISIS claimed responsibility for the attack through its Amaq news agency saying 'soldiers' had 'planted IEDs'

Police asks the public to dial 999 or the anti-terror hotline on 0800 789 321 if they see anything suspicious.

It was the middle of rush hour when the crude bucket bomb - which had a timer - went off at 8.20am inside a tube train packed with commuters, including children and a pregnant woman.

The device was hidden in a builder's bucket and could have killed dozens but failed to properly detonate and sent a 'wall of fire' through the carriage at Parsons Green, injuring at least 29 people.

Terrified passengers were left covered in blood with scorched hands, legs, faces and hair – others suffered crush injuries during a stampede as they 'ran for their lives' over fears the 'train would blow up'.

London Ambulance took 19 patients to hospitals, while the others went in themselves. The four hospitals dealing with patients were Imperial, Chelsea and Westminster, Guy's and St Thomas' and St George's.

Officers are tonight hunting for the bomber across London amid claims he could be armed and might have planted other explosive devices.

An officer at the scene told MailOnline: 'We believe there is a second bomb - there is a man with knives on the loose.'

In a pre-recorded television statement released around 8.30pm, May said military personnel would replace police officers 'on guard duties at certain protected sites which are not accessible to the public'.

Theresa May raises terror threat level to its highest possible Mrs May said in a statement from Number 10 - 'The Joint Terrorism Analysis Centre has now decided to raise the national threat level from severe to critical - this means their assessment is that a further attack may be imminent. 'The public will see more armed police on the transport network and on our streets, providing extra protection. 'This is a proportionate and sensible step which will provide extra reassurance and protection while the investigation progresses.' Advertisement

She said: 'The public will see more armed police on the transport network and on our streets, providing extra protection.

'This is a proportionate and sensible step which will provide extra reassurance and protection while the investigation progresses.'

Speaking moments afterwards, Assistant Commissioner Mike Rowley said: 'We are making excellent progress at the moment as we pursue our lines of inquiry to identify, locate and arrest those responsible.

'We have hundreds of police officers trawling through CCTV footage, detectives have spoken to tens of witnesses and we have taken a large number of calls to the hotline... from members of the public.

'Indeed members of the public have sent in so far 77 images and videos of the scene which they have sent in to our appeal website and these are now being assessed for evidential value.'

Mr Rowley said he was only aware of one device, and the remnants of that device are being examined by experts.

London Mayor Sadiq Khan told LBC radio 'there is a manhunt under way as we speak' and there have been no arrests. Mr Khan was later criticisd for using a TV interview to score political points about police cuts.

He said the events backed up his argument that the Metropolitan Police needed more money. But Tory MP Andrew Bridgen said: 'I would've thought Sadiq Khan would want to keep politics out of the terror attack'.

ISIS claimed responsibility for the attack this evening through its Amaq News Agency, saying its 'soldiers planted IEDs'. However, the group has often made false claims in the past.

Photographs show what experts believe is an 'unsophisticated' bomb in a flaming white bucket inside a Lidl freezer bag with Christmas lights protruding from the top - a type of fuse encouraged by ISIS in its online manuals.

Donald Trump tweeted just hours after the rush hour blast that police had the attacker 'in their sights' and should have been 'more proactive' in catching 'the loser'.

Scotland Yard hit back and said Mr Trump's comments were 'pure speculation' while senior officers refused to name the suspect.

Mrs May also hit out at the President's tweet, calling it 'unhelpful', and has this evening discussed the intelligence sharing between the two countries with the President in a telephone call.

This image was taken from the platform in the minutes after the terror attack and it remained alight until the fire service arrived

A forensics tent has been erected on the platform - although there have been no fatalities - and a single pair of shoes lies abandoned outside the door where the bomb ignited

Horrified witnesses on social media claim there was a stampede as people were 'screaming and running' off the trains, which was searched by heavily armed police officers today

A heavily armed officer wanders through the damaged train's carriages looking for more devices

The abandoned train at Parsons Green today after a terrorist left a bucket bomb on the carriage floor

Police believe the bomber may have exited the train (pictured) perhaps one or two stops before the bomb went off

Passengers on trains at Parsons Green were evacuated onto the track away to safety after London was hit by another terror attack

Passengers are ushered across the track by firefighters after getting trapped in the aftermath of the bombing

Witnesses to the explosion said there was a loud 'bang', a flash and then a ball of flame engulfed surrounding passengers on the 'packed' District Line train.

HOW RELEASING INFORMATION HELPED CATCH BARCELONA ATTACKER The failure of the Metropolitan Police to name the suspect contrasts sharply with the response to the last major terror attack in Europe, Barcelona in August. Just over an hour after the attack took place, Spanish police tweeted the public to say they were searching for the attacker and to avoid the area. Then, three hours after the attack, a photo of a suspect, Driss Oukabir, was released and circulated online. The release of the image caused Oukabir to come forward to his local police and tell officers his documents had been stolen. This was again revealed to the media as Oukabir's younger brother Moussa became the prime suspect. Advertisement

Luke Warsmey said: 'The explosion was like a large match going off at the end of the carriage. People just started sprinting. It was every man for himself when that happened. The burn victims had severe leg injuries.

'It was a very busy commuter train, young and old, school children going to their schools. I saw was nannies trying to look for kids, because of the rush of people just taking five and six year olds away from them and they were trying to look for them.

'There were lots of injuries from people being trampled on and everyone who had been close to it had the same burns to their head.'

Prime Minister Theresa May chaired a meeting of the Government's Cobra emergencies committee this afternoon to discuss the terrorist attack.

Mrs May later appealed to any members of the public with images of the incident to pass them to the police.

Armed Police, paramedics and firefighters were all said to be at the west London station within five minutes of the explosion.

A 100 yard cordon was erected around the station and a police helicopter was also overhead.

The Met confirmed it was a terrorist attack around 40 minutes later.

Scotland Yard said the area surrounding Parsons Green Tube station has been evacuated so specialist officers could 'secure the remnants of the improvised device and ensure it is stable'.

In the aftermath armed police swooped from the SO-15 counter-terrorism unit performed a hard-stop on a bus in nearby Chelsea Bridge Road. The call was linked to the terror attack but nothing suspicious was found on board.

Specialist officer have been examining the bomb and believe they will be able to gather crucial DNA evidence because it failed to properly detonate

Armed police swamped the area and there are claims that there is a suspect on the run who may also be armed

A team of paramedics walk towards the station to treat victims and St Mary's Hospital in Paddington have declared an emergency

Sniffer dogs are also searching around the cordoned off area amid claims that there are other devices

Specialist forensic officer, including some with expertise in dealing with bombings and chemical incidents, are combing the train for clues

Armed policemen stand by cordon near Parsons Green tube station - and the Met will flood London with them over the coming days

A police cordon remained outside Parsons Green Tube station on Friday afternoon following the blast during the morning rush hour

A forensic officer in blue overalls walks along the pavement near Parsons Green tube station as the investigation continues into the attack

Lidl will help police after their bag was used to house bomb Supermarket Lidl has offered to assist a police investigation into the terrorist incident on the London Underground, after one of its bags was apparently used to hold the improvised bomb. The German-owned grocery chain issued a statement just hours after social media photos of the affected District Line carriage showed a still-burning bucket inside a Lidl-branded reusable bag. 'We are shocked and concerned to have learned of an incident at Parsons Green this morning and our thoughts are with those affected,' Lidl UK said. 'We will, of course, support the authorities should they need our assistance in their investigations. We are closely monitoring the situation as it develops over the course of the day.' A spokesman for the supermarket also confirmed that what seemed to be an insensitive tweet, purportedly sent out by Lidl UK's twitter account on Friday morning, was fake. Twitter user @jesuiscanard appeared to retweet a Lidl UK tweet from 10:32am which read: 'We are proud to officially have the strongest bags. Great value for just 10p.' Advertisement

Emma Stevie, 27, described a 'human stampede' after the bomb went off. She said: 'I heard lots of screams and people saying “run, run”. We got out and then there was a human stampede, down the stairs.

'There were people lying underneath getting crushed, a big human pile-on. I wedged myself in next to a railing. I put myself in the foetal position. I kept thinking, “I'll be ok, I'll be ok”.

'There was a pregnant woman underneath me and I was trying really hard not to crush her.'

Richard Aylmer-Hall told Sky News: 'There were a few crush injuries on the stairs. People got squashed and crushed going down the stairs. Police evacuated everyone from the scene pretty quickly.

'There was screaming, pushing and shoving - it was a like there was a terrorist on the loose with a gun or something - lots of people were in tears. When it was all over lots of people were being comforted and looked after. It was total chaotic panic.

'A lady who had been on the same carriage as the device described it going off - a puff of smoke and flames coming out of it.'

Couple Lucy, 24 and Fabin, 29, were on their way to work when the explosion happened.

Lucy, who works in PR, said: 'We just heard screaming and sprinting, there was a stampede on the stairs and people were falling over, there was a schoolboy being lifted up after he had fallen down, he was in his school uniform, he must have been about ten, he was crying and distressed.'

Fulham fitness instructor Niyi Shokunbi, 24, was in the next carriage the moment the bomb went off.

He told MailOnline: 'I have never seen anything like it was like something out of a film. I thought it was an acid attack. It happened like bang within ten seconds, I just wanted to run.

'I went towards the carriage where the bomb went off a woman said you don't want to go in there. I saw a little boy with scratches on his face crying for his brother. A woman was bleeding. Everyone was running. I've never seen anything like it.'

There is terror and panic at the station this morning, with police officers consoling members of the public

An injured man is helped into an ambulance - one of 18 ferried by ambulance to hospitals across London. Four others went to A&E themselves

A family with young children look towards the station in the aftermath of the terror attack on London

Witnesses say people ran from the scene with 'blood on their face'

Armed Police, paramedics and firefighters were all said to be at the west London station within five minutes of the explosion

People were stranded after the bombing and the District Line is expected to be closed for at least today

Bomb disposal experts are at the scene amid fears there could be second bomb

Passengers ran onto the rail tracks to get away from the train as a fireball engulfed the carriage

Witnesses claim people were trampled on when they fled the train after hearing a 'whoosh' and seeing flames race towards them

Flames engulfed one carriage and raced along a train on a west London route to Parsons Green, forcing passengers to trample others as they rushed for an exit

Khan accused of cynical bid to link attack to police numbers Labour’s London Mayor was accused of cynically taking advantage of yesterday’s terror attack to score a political point about police cuts. Sadiq Khan used a television interview to criticise the lack of spending on officers. Even Mr Khan acknowledged the insensitive timing, saying: ‘Today may not be the day to say this at the Cobra meeting, but I’m not going to resile from what I’ve been saying over the last 16 months, which is that London needs more resources to keep our city safe.’ He said the events backed up his argument that the Metropolitan Police needed more money, adding: ‘Since 2010, we’ve lost hundreds of millions of pounds from the police budget.’ He told Sky News: ‘It’s simply not possible for a global city like London to carry on keeping our citizens, visitors and businesses safe if the Government carries on making the cuts they’ve been making.’ But Tory MP Andrew Bridgen criticised the Mayor. He said: ‘I would’ve thought Sadiq Khan would want to keep politics out of the terror attack – especially given his lamentable record on acid attacks and knife crime which have soared since he became Mayor of London.’ Advertisement Chef Marco's son sneers: Rich don't die as they don't take tube The son of chef Marco Pierre White caused outrage when he posted a vile tweet about the terror attack. Marco Pierre White Jr mocked passengers caught up in the bomb blast, suggesting that was why he doesn’t ‘take the tube’ – adding that ‘the rich don’t die’. He tweeted: ‘Parsons Green tube station this morning was targeted by terrorists, this is why I don’t take the tube #theRichDontDie.’ The reality TV star – whose father has an estimated fortune of around £30million – deleted the offensive tweet just a minute later, but was criticised by other social media users for his ‘lack of humility’. The 22-year-old later apologised in another tweet, saying: ‘I apologise for my tweet this morning, it was insensitive & ignorant. 'My thoughts & prayers are with those affected & injured by the attack.’ It is not the first time he has mocked those who take public transport. Last week he tweeted: ‘Lol I just heard the underground has been delayed ... this is the reason I don’t mingle with the peasants.’ Advertisement

People suffered burns from the explosion and others were hurt in the crush.

Rob Partinton, 24, from Harrow told MailOnline: 'We were literally about two minutes from Parsons Green when the train suddenly stopped.

'I saw people running on the track opposite direction towards Fulham Broadway, I could hear no screams but a lot of people running. We've been held at the station for the last half an hour. It's pretty busy, a lot of police around and police dogs.'

Another witness, Sham, said he saw a man with blood all over his face. 'There were loads of people crying and shaking,' he told Five Live.

Fairy lights have been used as detonators by extremist bombers before Pictures of the apparent home-made bomb seen after the explosion show a Lidl coolbag with a large paint tub inside and a string of Christmas tree lights hanging over the top. If the device does turn out to be a terrorist bomb, it would not be the first time extremists have used so-called 'fairy lights' to build a device. In May this year, a radicalised former doorman Zahid Hussain was found to have built an explosive device in his bedroom with fairy lights, shrapnel and a pressure cooker. He is said to have researched bomb-making techniques online, with police finding a wealth of notes and instructions at his home in Birmingham when he was arrested in 2015. Chief Superintendent Matt Ward, of West Midlands Police, said of Hussain's bomb at the time: 'Forensic examination of the pressure cooker found it contained mixed urea, nails, drills bits, nuts, bolts, steel sockets and diesel fuel. 'The Christmas tree lights also found at his address had been adapted so each one could be used as an explosive initiator or detonator. 'Examination of his computer discovered browsing history relating to terrorism including bomb making and bomb blast injuries, showing he had a consistent and continued interest in Chris Wildish, who was on the train, said he saw a 'device' in the last carriage. 'It was a white bucket, a builder's bucket, in a white Aldi bag or Lidl bag,' he told 5live. 'Flames were still coming out of it when I saw it and had a lot of wires hanging out of it - I can only assume it was done on purpose. 'It was standing against the door of the rear-most carriage.' Advertisement

'There were a lot of people limping and covered in blood. One guy I saw, his face was covered in blood - I've never seen anything like it.'

At the scene dozens of police and ambulances have continued to be called into the cordoned area. It is not known at this stage how many people are injured.

Specialist armed anti-terror units also swamped the area.

Chris Wildish, who was on the train, said he saw a 'device' in the last carriage.

'It was a white bucket, a builder's bucket, in a white Aldi bag or Lidl bag,' he told 5live.

'Flames were still coming out of it when I saw it and had a lot of wires hanging out of it'.

Sylvain Pennec, a software developer from Southfields, was around 10 metres from the source of the explosion when fire filled the carriage.

'I heard a boom and when I looked there were flames all around,' he said. 'People started to run but we were lucky to be stopping at Parsons Green as the door started to open.'

He described the scene of panic as commuters struggled to escape the carriage, 'collapsing and pushing' each other.

Mr Pennec stayed behind to take a closer look at what he believed was the source of the explosion.

'It looked like a bucket of mayonnaise,' he said. 'I'm not sure if it was a chemical reaction or something else, but it looked homemade. I'm not an expert though.'

Passengers on the train behind the affected Tube witnessed terrified passengers sprinting away up the tracks.

They were then held in their train for over an hour before being evacuated on to the tracks themselves.

Nicole Linnell, 29, who works for a fashion label, said: 'We saw people running down the tracks. About 30 or 40 people.

'They were running down the tracks outside our train.

'It was absolutely terrifying. Running on the tracks is the last thing you want to do so we were like 'What's going on?'

'After about an hour we were evacuated off the train on to the tracks. About 10 to 15 people at a time.'

Melanie Heyside had been at a gym nearby and intended to get on a District Line train to go to work.

She told Sky News: 'I just was about to open the doors to leave the studio and then all of a sudden Swat cars completely stormed and blocked the street and police jumped out with their armour and were telling people to 'move, to move'.

'So I was inside with a group of other people and we weren't really sure what to do.'

She said they were told to leave the area, which she added was populated by schoolchildren and others going to work, as quickly as possible.

Lady Margaret's School, next to Parson's Green tube station, put out an alert to concerned parents to say all children are okay and there are no absences.

'Crude' bucket bomb made with fairy lights could have killed DOZENS say experts as police reveal 21/7-style device failed to properly detonate Explosives experts say the Parsons Green bomb could have killed dozens if it had properly detonated at rush-hour this morning. Anti-terror police are now examining the bucket bomb which failed to fully go off on a tube train in west London as they try to track down the bomber. Photos of the explosive show a large builder's tub - believed be packed with explosives - inside a Lidl coolbag, with a string of Christmas tree lights, thought to have been a crude detonator, hanging over the top. Officers compared the device to those used in the failed 21/7 bombings, in which jihadis attempted to blow up tube trains. In that case, the bombs' detonators went off but the explosives themselves were not ignited. Photos of the bomb at Parsons Green show a builder's bucket inside a Lidl coolbag with apparent fairy lights hanging out of it. It is thought the bomb failed to fully detonate It is believed the bomb was left on the busy district line train from Wimbledon this morning before the bomber escaped. Police are analysing the device to track down the terrorist ISIS have encouraged followers to use the lights in bomb guides they post online, but the terror group have yet to claim responsibility for the attack. A timer is understood to have been found on the device, suggesting the terrorist left it on board the train and then got off. It also suggests it was intended to go off at busier stations further down the line. Terror expert Will Geddes said: 'My suspicion is that Parsons Green was not the intended target. 'Unless a person knows it, it is not going to mean a great deal to you - if it was Paddington or Notting Hill, they are internationally recognised names.' 'I think it was more a premature detonation than anything else. This could have been a lot worse. It could have killed a significant number of people.' Others say the bomb probably didn't detonated properly because it was badly made. Explosives expert Dr Sidney Alford told MailOnline: 'The fact that an initial bang was heard but the bomb did not even shatter the plastic bucket it was contained in suggests to me this could have been hydrogen peroxide. 'I can rule out other types of explosives as if the initial bang was heard with those they would have gone off completely and destroyed the bucket.' Flames engulfed one carriage and raced along a train on a west London route to Parsons Green, forcing passengers to trample others as they rushed for an exit Dr Alford said the bomb properly did not go off because it was poorly designed. Witnesses reported a 'strong, acrid chemical smell' in the carriage after the explosion. Major General Chip Chapman told Sky News: 'This doesn't look like a high-end explosive from ISIS such as TATP (triacetone triperoxide) or, if it was, it failed significantly, the booster or detonator didn't go off.' 'That said of course, the most devastating land-based terror attack in Europe, in Madrid, had a similar modus operandi.' He added: 'It's not a high explosive that functioned because the blast and shockwave would have killed multiple people.' Former Army bomb squad expert Chris Hunter told the channel the pictures reminded him of the devices which failed to go off during botched the 21/7 attacks. In that instance, a group of Islamic terrorists planned to carry out a copy-cat attack to 7/7, but although the detonator part of the bombs went off, they did not ignite the explosives and only one person was injured. Examining the image of the bomb, chemical weapons expert Hamish de Bretton-Gordon told MailOnline: 'It looks pretty unsophisticated. 'It could be an incendiary device with some sort of detonator in a big white plastic bucket, perhaps with some sort of chemical like ammonia nitrate, fertiliser bomb to cause an explosion.' He said the attack looked like 'classic jihadi terrorism' and the bomb could have been 'devastating' if it had detonated properly. Mr de Bretton-Gordon said the attack would raise further questions over whether the sale of certain chemicals should be more heavily regulated.' Describing the device, witness Sylvain Pennec said: 'It looked like a bucket of mayonnaise. I'm not sure if it was a chemical reaction or something else, but it looked home made.' The incident has been compared to the 21/7 attacks in which bombs were placed on the underground and the detonators went off, but did not ignite the explosives In that instance, the bombers Muktar Said Ibrahim (left) and Ramzi Mohammed were tracked down by police and convicted of terror offences It is not be the first time extremists have used so-called them to build a device. In May this year, a radicalised former doorman Zahid Hussain was found to have built an explosive device in his bedroom with fairy lights, shrapnel and a pressure cooker. He is said to have researched bomb-making techniques online, with police finding a wealth of notes and instructions at his home in Birmingham when he was arrested in 2015. Similarities between the device and that used in the Boston Marathon bombing in 2013 have also been drawn. In that case, timers were also used to allow the bombers to get away. However, in that case the explosives were in a pressure cooker. Advertisement

Transport for London said Tube services were suspended between Edgware Road and Wimbledon

Members of a bomb disposal squad stand in the street near Parsons Green tube station

Counter-terrorism police are monitoring events at Parsons Green and are now hunting at least one suspect

A number of commuters have been taken to hospital with serious facial burns, as police remain at the scene

There were reports of a man at the station with a knife in the aftermath of the explosion. Scotland Yard said they believe this is unrelated to the Tube incident

Pictures from the District Line train appear to show a burning plastic bucket stashed in a Lidl carrier bag, which exploded

A police officer and a sniffer dog stand in the street near Parsons Green tube station

People at the chaotic scene have been frantically calling relatives in the aftermath of the explosion

Police at the scene are keeping people away, moving them up Fulham Road and away from the station

Emergency services at the scene following a blast on an underground train at Parsons Green tube station in West London

Peter Crowley tweeted this photograph, with the caption: 'Charred head from the fireball at Parsons Green'

Dozens of police vehicles are at the scene as people are being urged to avoid the area

A London Fire Brigade spokeswoman said: 'We were called at 8.21am and we have information there was a fire on a train eastbound at the platform at Parsons Green'

Armed police are at the scene in London, as commuters have been evacuated

Images from the scene show emergency services and armed police

Social media users reported a 'stampede' around the underground station at rush hour

The London Ambulance Service was called at 8:20am and sent single responders in cars, ambulance crews, incident response officers and a hazardous area response team

People fled the Underground station in panic, amid reports there was an explosion

'Our hearts and prayers go out to the people of London': Trump walks back his controversial Twitter comments after claim that police had bomber 'in their sights' sparks phone confrontation with May

Theresa May rounded on Donald Trump yesterday after he claimed the Parsons Green bomber had been under surveillance by Britain’s security services.

In an extraordinary breach of diplomatic protocol, the US President took to social media within hours of the attack to claim the suspect was ‘in the sights of Scotland Yard’.

He later walked back on his controversial comments, tweeting: 'Our hearts and prayers go out to the people of London, who suffered a vicious terrorist attack.'

Earlier he wrote: ‘Another attack in London by a loser terrorist. These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!’

His comments drew a swift rebuke from the Prime Minister, who said: ‘I never think it’s helpful for anybody to speculate on what is an ongoing investigation.’ She later challenged the president in person when he called her to discuss the case.

Donald Trump on the White House lawn today where he insisted he had been briefed about Parsons Green and said the suspect was known to police

Theresa May (pictured in No 10 this afternoon) said any speculation was unhelpful when asked about the President's tweets on the Parsons Green attack

Trump tweeted: 'Another attack in London by a loser terrorist. These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!'

Mr Trump later walked back on his controversial comments, tweeting: 'Our hearts and prayers go out to the people of London, who suffered a vicious terrorist attack'

Met terror chief Mark Rowley updated the media on the investigation this morning (pictured) but has not given any details of any man hunt

A Scotland Yard spokesman also criticised Mr Trump, saying: ‘The comments are unhelpful and pure speculation. If anyone has got any evidence or information, please contact the anti-terrorism hotline.’

rs May’s former chief-of-staff Nick Timothy commented on Twitter, saying: ‘True or not – and I’m sure he doesn’t know – this is so unhelpful from leader of our ally and intelligence partner.’

Mr Trump appeared unconcerned about his diplomatic slip. Asked about the terror attack by reporters outside the White House, he said: ‘It’s a terrible thing.

‘It just keeps going and going, and we have to be very smart, we have to be very, very tough. Perhaps we are not nearly tough enough. It’s just an absolutely terrible thing. In fact, I’m going to call the Prime Minister right now.

President Donald Trump has claimed Scotland Yard knew ahead of time about a bomber or bombers who set off a crude incendiary bomb Friday morning on London's 'Tube' subway

Trump added: 'Loser terrorists must be dealt with in a much tougher manner. The internet is their main recruitment tool which we must cut off & use better!'

Theresa May's former adviser Nick Timothy reacted to Trump's intervention by saying the president 'doesn't know' anything: 'This is so unhelpful from leader of our ally and intelligence partner'

'We have to be tougher and we have to be smarter.’ He told reporters that he had been briefed on the explosion, but did not provide further details.

His national security adviser HR McMaster suggested later that Mr Trump was speaking generally.

Noting that law enforcement agencies have been working to combat terrorism for years, Mr McMaster said: ‘I think if there was a terrorist attack here, God forbid, that we would say that they were in the sights of the FBI.’

He added: ‘I think he means generally that this kind of activity is what we are trying to prevent.’

The controversy threatened to reopen the row between the UK and the US over the leaking of sensitive police information that led to the temporary suspension of security co-operation in the wake of the Manchester bombing.

The president linked Friday's attack to his controversial travel ban, saying it 'should be far larger, tougher and more specific – but stupidly, that would not be politically correct!'

He also drew attention to the military action against ISIS and should the US should get 'nasty'

Labour MP Stephen Doughty, a member of the home affairs select committee, said last night Mr Trump’s intervention ‘has the potential to not only undermine a vital relationship, but also to prejudice investigations into this and other incidents’.

UBER HELPS STRICKEN RAIL PASSENGERS Uber has confirmed it is helping people affected by tube cancellations. The company tweeted this morning: 'We are aware of an incident at Parsons Green. 'We have turned off dynamic pricing and will refund all journeys from the affected area. ' Advertisement

Liberal Democrat home affairs spokesman Sir Ed Davey said: ‘It is insulting to the victims of this attack that Donald Trump is already using it to try and further his divisive political agenda. Once again, Trump has shown he is not fit for the office of US President.’

London Mayor Sadiq Khan, who clashed with Mr Trump over his response to the London Bridge terror attack, would not be drawn on the president’s comments. ‘I’ve simply been too busy to look at my Twitter,’ he said. ‘My priority is making sure that we do what we can to keep Londoners safe.’

A City Hall source said: ‘He hopes people don’t speculate on things before we know the full facts. It’s clear what he thinks about that.’

In May, British police temporarily suspended intelligence sharing after a series of damaging US leaks about the investigation into the Manchester bombing.

Images of the remnants of terrorist Salman Abedi’s backpack and a diagram showing where his victims died were handed to a US newspaper.

Timeline of terror: Parsons Green train bombing is FIFTH attack to hit Britain in 2017 March 22: Five people are killed in a car and knife attack in Westminster. Khalid Masood drove a hire car over Westminster Bridge, near the Houses of Parliament, mounted the pavement and hit pedestrians before crashing into railings outside the Palace of Westminster. He stabbed Pc Keith Palmer, 48, to death. Also killed in the atrocity were US tourist Kurt Cochran, Romanian tourist Andreea Cristea, 31, and Britons Aysha Frade, 44, and 75-year-old Leslie Rhodes. Masood was shot dead by police. March 22: Five people were killed in a car and knife attack in Westminster, London May 22: Twenty-two people - including children - are killed in a bombing at a pop concert in Manchester. Lone suicide attacker Salman Abedi detonated an explosive device as crowds of music fans, many of them youngsters, left Manchester Arena following a performance by US singer Ariana Grande. May 22: Twenty-two people - including children - are killed in a bombing at a pop concert in Manchester Lone suicide attacker Salman Abedi detonated an explosive device as crowds of music fans, many of them youngsters, left Manchester Arena June 3: Eight people are killed in a terror attack around London Bridge. A van ploughed into people on the bridge before the three attackers carried out a knife rampage in Borough Market. The perpetrators - Khuram Butt, 27, Rachid Redouane, 30, and Youssef Zaghba, 22 - were shot dead by police. Khuram Butt, 27, Rachid Redouane, 30, and Youssef Zaghba, 22 - were shot dead by police June 19: One man dies and several others are injured after a man allegedly rams his van into worshippers in north London. Darren Osborne, 47, of no fixed address in Cardiff, is charged with murder and attempted murder after being accused of carrying out a premeditated attack on Muslims as they left a mosque on Seven Sisters Road, Finsbury Park. June 19: One man dies and several others are injured after a man allegedly rams his van into worshippers in north London Police warned there is no such thing as a 'typical terrorist' after official statistics showed rises in numbers detained across ethnicities and age groups. There were 379 arrests for terrorism-related offences in the year ending June 2017, the highest number in a 12-month period since data collection began in 2001. Police and MI5 are running 500 investigations involving 3,000 individuals at any one time, while there are also 20,000 former 'subjects of interest' whose risk must be kept under review. Advertisement

The fairy lights bomber: Jihadi used similar device in plot two years ago In 2015, Zahid Hussain, pictured right, used adapted Christmas tree lights, shrapnel and a pressure cooker to improvise a bomb. When officers raided his home in the Alum Rock area of the city, they found his room littered with text books detailing guerrilla warfare techniques and small arms combat, further bomb making instructions and dismantled electrical items such as doorbells and alarm clocks. He bought most of the items he used for his bombs over the internet. Chief Superintendent Matt Ward, of West Midlands Police, said of Hussain's bomb at the time: 'Forensic examination of the pressure cooker found it contained mixed urea, nails, drills bits, nuts, bolts, steel sockets and diesel fuel. 'The Christmas tree lights also found at his address had been adapted so each one could be used as an explosive initiator or detonator. 'Examination of his computer discovered browsing history relating to terrorism including bomb making and bomb blast injuries, showing he had a consistent and continued interest in terrorism and conflict.' The Christmas tree lights found at Hussain's address, in the Alum Rock area of Birmingham, had been adapted so each one could be used as an explosive initiator or detonator Advertisement

A police officer escorts an injured woman from the scene at Parsons Green Underground Station

Other commuters at the scene said they were 'thrown around and crushed' by panicked crowds shouting 'there's a man, there's a man' before running from the area

Dozens of commuters made a '100 metre sprint' after a large flash engulfed the 8.20am train as it pulled into Parsons Green station

People reported being crushed on the concrete stairs with TfL staff were doing their best to get control

Witnesses said 'In the immediate seconds there were people running and shouting, it was just like where do you run to?'

People on their way to work were 'thrown around and crushed' by panicked crowds

Witnesses claim at least 30 commuters including school children were injured after a homemade bomb exploded on a packed commuter train

One man said he had seen people lying on the floor covered in blood

Flames engulfed one carriage and raced along a train on a west London route to Parsons Green, forcing passengers to trample others as they rushed for an exit

Armed Police, paramedics and firefighters were all said to be at the west London station within five minutes of the explosion

'Come round, the kettle's on!' Unfazed Londoners are praised for 'beautiful response' to Parsons Green bucket bomb by offering to make cups of tea and opening their homes for survivors

Defiant Londoners have reached out and offered to help anyone caught up in the Parsons Green terror attack.

People across the capital have offered to make tea and open up their homes to anyone wounded in the blast on a train at Parsons Green in west London.

Taxi drivers have also come to the aid of those affected, offering free journeys while Facebook users are inviting victims in to shelter, rest and charge their phones.

Social media awash with people offering to 'put the kettle on' for those affected by the Parsons Green bomb blast

Nearby taxi company Hayber Cars has offered its services free of charge, while Chelsea and Fulham Dentist, has also offered people a place to shelter.

Jan Ståhlberg‏ tweeted: 'Classic British response to an emergency & major incident: 'I'll put the kettle on'. Compassion and Communities come together.'

Anthony J Myers added: 'Thank you to TfL staff, emergency services, security services and the Londoners of #ParsonsGreen who have offered to put the kettle on.'

Kind-hearted Debbie Clark, 57, has opened up her home on Kelvedon Road as a makeshift hospital while a police hunt is underway for the perpetrators behind the terror incident.

The mother of two woke up to hear banging at her front door from her neighbour Princess Stafford, who is deaf and mute and had been badly injured in a stampede as hundreds rushed out of the station following an explosion.

Ms Clark said: 'I woke up to banging and she was at my door crying and distressed.'

People across the capital have offered to make tea and open up their homes to anyone wounded in the blast on a train at Parsons Green in west London

Across the road, Ms Clark said she saw three girls opposite her home, one was crying and said there were all 'as white as a sheet'.

Taking them into her home, she gave them water and called their parents. She said: 'they are just in shock. They said it happened so quickly, they just wanted to get out of there. One was from Sheffield, another from Surrey.'

She said: 'I brought them all into my home, called the police and their parents. I just wanted to do something, you feel so helpless. I've lived here all my life and was born in Parson's Green, you never expect something like this to happen.'

Flames engulfed one carriage and raced along a train on a west London route to Parsons Green, forcing passengers to trample others as they rushed for an exit

Armed Police, paramedics and firefighters were all said to be at the west London station within five minutes of the explosion

Her neighbour Princess is currently on Ms Clark's balcony with two chairs creating a makeshift stretcher with a suspected leg injury.

The 32-year-old was pushed to the floor by panicked commuters this morning as she waited to board a train at Parson's Green to take her to work.

She told MailOnline how she was knocked to the ground and trapped. She said: 'I couldn't move, there were people on top of me and walking over me.'

The rush was so great she was pushed back to the stairwell, she said.

With tears in her eyes, she told MailOnline how she couldn't breathe because of the number of people passing over her.

This afternoon she waits to be taken to hospital at Ms Clark's home. She was told by London Ambulance they could be waiting for up to four hours.

Ms Clark said: 'They are going to send a non emergency could take two to four hours because there have been serious injuries we understand. She can't communicate she can't hear and talk, good job I was in I am so glad I was in for her.'

A number of commuters have been taken to hospital with serious facial burns, as police remain at the scene

Speaking this morning, government minister Boris Johnson called on people to remain calm

Bomb disposal experts are among emergency services at the scene amid fears of more bombs

Transport for London said Tube services were suspended on that section of the underground

A woman walks with a young boy through west London as armed police stand guard nearby

Pictures posted on social media showed wires protruding from a flaming bucket inside a plastic carrier bag on the floor of a carriage.

The Met added: 'It is too early to confirm the cause of the fire, which will be subject to the investigation that is now under way by the Met's Counter Terrorism Command.'

Investigators will be scouring CCTV and taking statements from dozens of witnesses as they attempt to piece together the lead-up to the explosion.

The device will be forensically assessed after being made safe, while police will be urgently trying to establish whether someone attempted to detonate it, and whether they were present at the scene.

Heavily-armed police were drafted in to assist the investigation at Parsons Green today

Armed police boarded the train in the incident as the hunt for the bomber was stepped up

Paramedics in bullet-proof vests were guarded by armed police at the scene this morning

The scenes of panic evoked memories of the July 7 atrocities in 2005, when suicide bombers killed 52 people in a series of co-ordinated attacks across the transport network.

Two weeks later, a group of men attempted to set off rucksack devices but the bombs failed to go off.

The emergency at Parsons Green will spark another huge counter-terrorism probe as security services confront an unprecedented threat.

Four attacks - at Westminster, Manchester, London Bridge and Finsbury Park - have hit Britain already this year.

Authorities have foiled 19 plots since the middle of 2013 - including six since the Westminster atrocity in March.

An armed police officer stands guard after an incident on a tube train at Parsons Green station

Security has been stepped up around the capital as police attempt to find the bomber

The incident comes a day after figures revealed terror-related arrests in Great Britain have hit a new record high, with suspects held at a rate of more than one every day.

Police warned there is no such thing as a 'typical terrorist' after official statistics showed rises in numbers detained across ethnicities and age groups.

There were 379 arrests for terrorism-related offences in the year ending June 2017, the highest number in a 12-month period since data collection began in 2001.

Police and MI5 are running 500 investigations involving 3,000 individuals at any one time, while there are also 20,000 former 'subjects of interest' whose risk must be kept under review.