This heartbreaking photograph shows heroic police dog Diesel moments before she was blown up by a suicide bomber during the siege in Paris.

The seven-year-old Belgian Shepherd died this morning in a firefight with suspected ISIS militants behind the Paris massacre who were holed up in a flat.

She was sent in to the building to sniff out booby traps but was blown to pieces when a woman came out firing her AK-47 at police and then detonated her suicide vest.

Tributes quickly poured in to the much-loved canine who had been decorated with service medals after a distinguished career in the force.

One police handler said it was 'a little like losing one of our colleagues' while a Twitter user said Diesel had 'died to defend our colours'.

Diesel's death sparked a wave of mourning across social media, under the Twitter hashtag #JeSuisChien.

The hashtag, which means I am a dog and was trending on Twitter, is a reference to the worldwide cry of solidarity 'Je Suis Charlie' in the wake of the terror attacks on Charlie Hebdo magazine in January.

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Final moments: Diesel (centre) is seen being led towards the flat to sniff out booby traps minutes before she was killed by a jihadi bride who came out firing an AK-47 at police then detonated her suicide vest

Decorated: Seven-year-old police dog Diesel (pictured with her service medals in image identified by police officers at the scene) died during a firefight with suspected ISIS militants behind the Paris massacre

The official profile for Police Nationale tweeted that Diesel 'was killed by terrorists in the current operation in Saint-Denis'.

A source told MailOnline: 'When the policemen arrived with the dog, the dog came in first and was immediately killed. The French people are sad about her death.'

The force said that 'assault and explosives' search dogs are indispensable to the work of the French anti-terror unit known as RAID.

Sky News anchor Kay Burley, who was mocked this week for tweeting a picture of a dog in Paris with the caption ‘sadness in his eyes’, has joined the Twitter trend.

She tweeted a Police Nationale photograph of a force dog in honour of Diesel, with just the hashtag #JeSuisChien.

More than 100 armed officers stormed a flat in Saint-Denis this morning believing Paris massacres mastermind Abdelhamid Abaaoud, 27, was inside with six other terrorists - but the French authorities will not say if he was there or if he is dead or alive.

A female terrorist believed to be Abaaoud's jihadi bride or cousin blew herself up with a suicide vest and another suspect died during the six-hour siege where five people were taken alive and arrested. Two more suspects were held 'nearby'.

A wave of mourning swept social media in response to Diesel's death, under the hashtag #JeSuisChien

Lotfi, a 50-year-old who was in the area, said: 'I heard police officers talking to a woman with long blonde hair.

'I think she was the kamikaze. They told her not to lower her arms, to keep her hands up in the air, and then there was a massive explosion.

'I think that's when she detonated her bomb. It really was a very loud explosion.'

'Lots of windows on the street were shattered, and then the firefight started and it was going on nonstop.'

The Twitter profile for Police Nationale tweeted this image another police dog while paying tribute to Diesel

SNIFFER DOGS PLAY A VITAL ROLE IN CRIMINAL AND MILITARY PROBES Sniffer dogs have played a vital role in criminal investigations for decades thanks their unrivalled sense of smell. While the average human has around five to 10million olfactory cells in their nose, a dog has as many as 200 million. Police have long trained canines to detect illicit substances such as drugs, but in recent years they have also been used in anti-terror and military operations to sniff out the smallest traces of explosive materials. Generally, training will take place from a young age and involve rewarding them with a toy or treat when they encounter the scent. But it is vital that they are fully trained not to touch any substance they locate in case it is designed to explode on impact. Training will very often continue throughout their careers to ensure their skills are up to scratch. In the case of Diesel, she had apparently been used during the siege to sniff out improvised explosives devices (IEDs) that may have been set as booby-traps at the entrance of the building by the jihadis. Sniffer dogs are also used in a similar vein in war zones. Advertisement

Lofti, who would not offer his surname, said he saw Diesel blown to pieces.

State broadcaster France 2 has claimed the group was a 'fourth unit' on top of the three who killed 129 on Friday and were planning simultaneous attacks with AK-47s and bombs on Charles de Gaulle airport and the Quatre Temps shopping centre in the city's business district, Le Défense.

The Saint-Denis siege started at 4.25am when SWAT teams and special forces surrounded the building after security services hunting for Abaaoud spent days watching flats and tapping phones.

The stand-off ended as a bloodied and half-naked suspect was dragged out of the apartment close to the Stade de France at 10.24am.

At least five police were injured in the ferocious gunfight including one shot in the foot seen being carried from the scene.

Witnesses told MailOnline their street was 'turned into a warzone' after long periods of machine gun fire and at least seven large explosions, caused by the suicide bomber and hand grenades.

There were no hostages involved.

It came a Europe-wide alert was put out for a Citroen Xsara car that could be carrying Salah Abdeslam, the fugitive wanted in the Paris attacks, a Spanish security official said.

It was sent by Spanish authorities to border control police in the north-eastern Catalonia region next to France.

The security official confirmed the document was authentic but said the bulletin was sent to authorities across Europe and not only to Spain.

Mystery suspect: Hooded police officers pull a man arrested in the gun battle through crowds of other officers and soldiers as the Saint-Denis siege ended after six hours

Drama: The terror suspect was dragged from the building and broken glass with no trousers on - presumably in case he was wearing a suicide belt - as police trained their weapons on the flat

As the Saint-Denis siege ended after six hours this morning, it was revealed:

Paris massacres mastermind Abdelhamid Abaaoud, 27, was believed to be inside the safehouse at centre of the raid;

Police and secret services were watching several flats in Saint-Denis and had tapped phones in the area before they swooped at 4.25am;

Operation became more important after a tip-off that the Paris terror cell were about to launch a new attack on city's business district, La Defense;

Two terror suspects have been killed. One was a female suicide bomber who blew herself up. French and Belgian media have reported she is Abaaoud's wife or a cousin. The other fatality was a man killed by a grenade;

Two of the arrested terror plotters have been shot in the arm and are being operated on at a secure hospital in Bobigny, Paris;

Seven people have been arrested. Five were held in the flat or the 'rubble' inside apartment block and two more were held nearby;

Five police officers were injured. A Belgian Shepherd sniffer dog called Diesel was sent in to the block and killed by the terror cell;

French government confirms that all 129 victims of Friday's attacks have now been identified;

David Cameron tells MPs one Briton died – Nick Alexander - three have been released from hospital and further 15 being treated for trauma.

Paris prosecutor Francois Molins said authorities are still working to determine the fate of Abaaoud - and identify those killed and arrested.

He said confirmed three suspected jihadis were held in the flat and two more 'as they tried to hide in the rubble' of the block.

In their sights: Police move in on the apartment where the female suicide bomber blew herself up after firing an AK-47 machine at officers. At least one other jihadi is also dead since the stand-off started at dawn

Arrests: Seven people in total have been arrested in the operation including two people away from the under siege flat, left outside a shopping centre and right near the apartment block

Map: The raid was on a flat in the north of Paris - close to the three attacks close to the Stade de France - and not far from the shootings and suicide attacks on Bataclan and a series of bars, restaurants and cafes

TIMELINE: HOW THE SIX-HOUR SIEGE OF SAINT-DENIS UNFOLDED 4.25am (Local time) French police and security forces launch a major operation in the north Paris suburb of Saint-Denis. Abdelhamid Abaaoud, mastermind of Friday's attacks, is its target. Scores of police officers storm the building, but are held back when they meet heavy gunfire suffer several casualties. A large explosion is heard. 5:55am Trucks carrying French soldiers and a number of ambulances and fire engines are seen rushing towards Saint Denis. Surrounding roads are sealed off and residents are told to stay indoors. 6.27am A helicopter is seen circling over the apartment block and a pedestrian area at the centre of the siege. More police reinforcements arrive at the scene. 7.20am Intense gunfire and several explosions are heard in Saint-Denis, with some people claiming to have heard the sound of grenades. Police in riot gear move to clear civilian bystanders from the streets. 7.30am As the siege enters its third hour, seven explosions rock Saint-Denis and witnesses close to the building report the sound of grenades coming from the apartment block. One explosion was from a woman detonating a suicide vest. 8.20am Police announce that two suspects - a man and a woman - were killed in the operation and two suspects detained, although it is not known if Abaaoud is among them, dead or alive. 9.00am Three more suspects from flat are arrested another man and woman are arrested nearby. 9.30am One suspect remains in the apartment five hours after the operation began. The number of arrests rises to five, including one woman. 10.00am French authorities confirm the death of a police dog in the operation and a police officer is shot in the foot 10.34am Siege ends as a man with no trousers on is dragged from building Advertisement

He said: 'It is currently impossible to give the identify of those arrested, which is being verified. Everything will be done to work out who is who and thanks to forensics who and was in the apartment'.

Mr Molins said police began the raid on Wednesday after gathering information that he could be in a safehouse apartment in Saint-Denis. Mr Molins said the information was collected from tapped telephone conversations, surveillance and witness accounts.

He told reporters after the operation was over that authorities are still working to determine who was inside.

French Interior Minister Bernard Cazeneuve arrived in Saint-Denis and said: 'I would like to pay tribute to all those involved in the operation, 110 in total, who acted with bravery and under heavy fire in conditions that they had never experienced before.

'I would also like to pay tribute to the cool-headedness of St Denis residents. They also contributed to the success of the operation'.

Armed police appeared on a street outside the Saint-Denis flat before dawn today and then at least three trucks of soldiers and special forces arrived as back up.

Witnesses told MailOnline said there were long periods of intense machine gun fire and at least seven large explosions.

Lotfi, a 50-year-old who was in the area, said: 'I heard police officers talking to a woman with long blonde hair.

'I think she was the kamikaze. They told her not to lower her arms, to keep her hands up in the air, and then there was a massive explosion. I think that's when she detonated her bomb. It really was a very loud explosion.

'Lots of windows on the street were shattered, and then the firefight started and it was going on nonstop.'

Lofti, who would not offer his surname, said he saw a police dog called Diesel blown to pieces. The German Shepherd was there to sniff out explosives.

One of the arrested suspects is the man who appears to have rented the flat to the terror cell.

Jawad Ben Dowt, 30, admitted in an interview near the under siege apartment on Rue de Corbillon he handed it over to two men 'who came from Belgium' two days ago.

He said: 'A friend of mine asked me to host two of his buddies for a few days.

'I said there was no mattress, they told me 'it's okay', they just wanted water and to pray. My friend said they were from Belgium.

'I was asked to a favour and I said yes. I was not aware that it was terrorists' - moments later police grabbed him and put him in handcuffs.

A female friend of his who was also held said she stayed there last week and described it as a 'squat' and said the Belgian men arrived on Monday.

A woman living below the under-siege flat with her young baby described being 'woken up by an explosion'.

Investigation: After the siege ended this morning a huge team of forensics started work outside the flat - marking out spent bullets with numbers next to them with a bloodied blue mattress thrown out of the window of the building (bottom of picture)

Secretive: French medics were ordered to put up sheets as some seven people arrested were transferred to Bobigny hospital. Two have been shot in the arm and are being operated on at a secure hospital in Bobigny, Paris

She told French broadcaster BMFTV: 'I awoke to an explosion. After that I heard gun shots and there was lots of shooting. The terrorists were fighting at the police and the police were firing back.

'There were shots, explosions. We didn't know where to go. My son and I were in panic.

'There was dust falling from the ceiling because of the explosions. I kept shouting 'If you're from the police, please help me. I'm here with my baby. But they kept shooting and shooting'.

Residents said they were first woken by an explosion which shook the neighbourhood at about 4am (3am GMT) as police surrounded the flat, although it is not known what led them to the building.

Witnesses say this was followed by an hour of automatic gunfire and explosions as an intense firefight ensued between police and the suspects holed up in the apartment.

Neighbour Amine Guizani said: 'They were shooting for an hour. Nonstop. There were grenades. It was going, stopping. Kalashnikovs. Starting again.'

Teams of armed police appeared on a street outside the Saint-Denis flat before dawn today and then at least three trucks of soldiers and special forces arrived as back up.

Police cordoned off the area nearby, including a pedestrian zone lined with shops and 19th-century apartment buildings and cleared people from the streets, pointing guns at curious residents to move them off the roads.

Sporadic bangs and blast continued and at 7.30am French time at least seven explosions shook the centre of Saint-Denis.

A woman who may be Abaaoud's wife is said to have fired her AK-47 at police before blowing herself up with a suicide vest as an assault squad stormed the apartment block. The siege ended at 10.34am.