Survivors of the Manchester attack have told how they watched victims die as they waited for medical attention, amid an investigation into the emergency response.

Salman Abedi’s homemade device killed 22 people including children as young as eight and injured 500 more in the atrocity, which was claimed by Isis.

Criticism quickly turned to the security services after it emerged that Abedi was known but not considered an imminent threat – despite his trips to war-torn Libya and intelligence over suspicious behaviour.

But witness accounts from the terror attack have also raised questions over the emergency services’ response at Manchester Arena on 22 May.

Phil and Kim Dick, from Bradford, were waiting in the venue’s foyer for their daughter and granddaughter to leave the Ariana Grande concert when the bomb was detonated.

As only three paramedics entered the area, they told the BBC some injured victims waited more than an hour to be evacuated outside the blast zone for full treatment.

Mrs Dick said a girl with “horrific” injuries – who survived – collapsed in front of her with severe burns and bleeding from her arm, mouth and leg.

“I just kept shouting ‘we need paramedics, we need paramedics now’ and [the armed police] said ‘we’re just making sure there’s no more bombs’,” she added.

Mother claims she was stood just 15ft from Manchester Arena suicide bomber

“We were just keeping [victims] alert and talking to them…it was just over an hour.”

Mr Dick said that around an hour and 10 minutes after the explosion he was told the decision had been made to evacuate casualties outside, where 56 ambulances were waiting to treat them.

“The longer it went on the more silent it became. It was really eerie and people who I had seen a little earlier, who were severely injured, were now dead,” he added.

“There was just too much for three paramedics to deal with.”

The North West Ambulance Service NHS Trust (NWAS) said the first clinician was on the scene within four minutes of the 999 call and that the three paramedics who entered the foyer were triaging patients.

“We are extremely proud of the response that we gave on the evening of the tragic events in Manchester,” a spokesperson said.

“Our staff risked their lives to help others and undoubtedly lives were saved due to their heroic actions.

Manchester explosion in pictures Show all 37 1 /37 Manchester explosion in pictures Manchester explosion in pictures People running down stairs as they attempt to exit the Manchester Arena after a blast, where U.S. singer Ariana Grande had been performing, in Manchester Twitter/@ZACH_BRUCE/ via REUTERS Manchester explosion in pictures Helpers attend to people inside the Manchester Arena after a suspected suicide bomber detonated an explosive device at the end of an Ariana Grande concert, killing 22 people PA wire Manchester explosion in pictures Armed officers guard outside a hotel near the Manchester Arena following reports of an explosion, in Manchester, Britain EPA Manchester explosion in pictures Police officers are seen outside the Manchester Arena, where U.S. singer Ariana Grande had been performing, in Manchester, northern England Reuters Manchester explosion in pictures MANCHESTER, ENGLAND - MAY 23: Police escort members of the public from the Manchester Arena on May 23, 2017 in Manchester, England. An explosion occurred at Manchester Arena as concert goers were leaving the venue after Ariana Grande had performed. Greater Manchester Police have confirmed 19 fatalities and at least 50 injured. (Photo by Christopher Furlong/Getty Images) Getty Images Manchester explosion in pictures MANCHESTER, ENGLAND - Emergency services arrive close to the Manchester Arena on May 23, 2017 in Manchester, England. There have been reports of explosions at Manchester Arena where Ariana Grande had performed this evening. Greater Manchester Police have have confirmed there are fatalities and warned people to stay away from the area. (Photo by Dave Thompson/Getty Images) Getty Images Manchester explosion in pictures MANCHESTER, ENGLAND - MAY 23: Police escort members of the public from the Manchester Arena on May 23, 2017 in Manchester, England. An explosion occurred at Manchester Arena as concert goers were leaving the venue after Ariana Grande had performed. Greater Manchester Police have confirmed 19 fatalities and at least 50 injured. (Photo by Christopher Furlong/Getty Images) Getty Images Manchester explosion in pictures Medics deploy at the scene of a reported explosion during a concert in Manchester, England on May 23, 2017. British police said early May 23 there were "a number of confirmed fatalities" after reports of at least one explosion during a pop concert by US singer Ariana Grande. Ambulances were seen rushing to the Manchester Arena venue and police added in a statement that people should avoid the area / AFP PHOTO / Paul ELLIS (Photo credit should read PAUL ELLIS/AFP/Getty Images) AFP/Getty Images Manchester explosion in pictures Police and fans close to the Manchester Arena, after reports of an explosion Getty Images Manchester explosion in pictures There have been reports of explosions at Manchester Arena where Ariana Grande had performed Getty Images Manchester explosion in pictures Police deploy at scene of explosion in Manchester, England, at a concert in Manchester Arena AFP/Getty Images Manchester explosion in pictures Police stand by a cordoned off street close to the Manchester Arena Getty Images Manchester explosion in pictures Police deploy at scene of explosion in Manchester, England AFP/Getty Images Manchester explosion in pictures Police deploy at scene of a reported explosion during a concert in Manchester, England, on May 23, 2017. British police said early May 23 there were "a number of confirmed fatalities" after reports of at least one explosion during a pop concert by US singer Ariana Grande. Ambulances were seen rushing to the Manchester Arena venue and police added in a statement that people should avoid the area AFP/Getty Images Manchester explosion in pictures An ambulance drives away from the Manchester Arena, where U.S. singer Ariana Grande had been performing, in Manchester Reuters Manchester explosion in pictures Police escort members of the public from the Manchester Arena in Manchester, England. Getty Images Manchester explosion in pictures A woman sits in the street in a blanket near the Manchester Arena as police guard the area following reports of an explosion, in Manchester, Britain EPA Manchester explosion in pictures Two women wrapped in thermal blankets stand near the Manchester Arena, where US singer Ariana Grande had been performing, in Manchester Reuters Manchester explosion in pictures A Royal Logistic Corps (RLC) bomb disposal robot is unloaded outside the Manchester Arena following reports of an explosion, in Manchester. At least 19 people have been confirmed dead and others 50 were injured, authorities said. It is being treated as a terrorist incident until police know otherwise EPA Manchester explosion in pictures A Royal Logistic Corps (RLC) bomb disposal robot is unloaded outside the Manchester Arena following reports of an explosion, in Manchester EPA Manchester explosion in pictures Members of the public receive treatment from emergency service staff at Victoria Railway Station close to the Manchester Arena on May 23, 2017 in Manchester, England. There have been reports of explosions at Manchester Arena where Ariana Grande had performed this evening. Greater Manchester Police have have confirmed there are fatalities and warned people to stay away from the area Getty Images Manchester explosion in pictures Armed police after a suspected terrorist attack at the Manchester Arena at the end of a concert by US star Ariana Grande left 19 dead PA wire Manchester explosion in pictures Emergency services arrive close to the Manchester Arena in Manchester Getty Images Manchester explosion in pictures An amoured police vehicle patrols near Manchester Arena in Manchester Getty Images Manchester explosion in pictures A man carries a young girl on his shoulders near Victoria station in Manchester AFP/Getty Images Manchester explosion in pictures Police officers stand at the Miller Street and Corporation Street Crossroads, in front of the Manchester Arena in Manchester, England Getty Images Manchester explosion in pictures Police block a road near to the Manchester Arena in central Manchester, England AP Manchester explosion in pictures Armed police patrol near Victoria station in Manchester, northwest England. Twenty two people have been killed and dozens injured after a suspected suicide bomber targeted fans leaving a concert of US singer Ariana Grande in Manchester Getty Images Manchester explosion in pictures Police forensic officers leave the Manchester Arena as they investigate the scene of an explosion in Manchester Getty Images Manchester explosion in pictures A forensic officer collects evidence on a walkway between Victoria station and Manchester Arena following a deadly terror attack in Manchester, Getty Images Manchester explosion in pictures A woman and a young girl wearing a t-shirt of US singer Ariana Grande talks to police near Manchester Arena following a deadly terror attack in Manchester, Getty Manchester explosion in pictures epaselect epa05982725 Susan Walton and daughter Katie, 10 (pictured), who attended the concert of Ariana Grande at the Manchester Arena, are seen in Manchester, Britain, 23 May 2017. According to a statement released by the Greater Manchester Police on 23 May 2017, police responded to reports of an explosion at Manchester Arena on 22 May 2017 evening. At least 19 people have been confirmed dead and around 50 others were injured, authorities said. The happening is currently treated as a terrorist incident until police know otherwise. According to reports quoting witnesses, a mass evacuation was prompted after explosions were heard at the end of US singer Ariana Grande's concert in the arena. EPA/NIGEL RODDIS EPA Manchester explosion in pictures Mayor of Greater Manchester Andy Burnham and Manchester City Council Leader Sir Richard Leese speak to the media outside Manchester Town Hall after a suicide bomber killed 22 people, including children, as an explosion tore through fans leaving a pop concert in Manchester Dave Higgens/PA Wire Manchester explosion in pictures The media gather behind a police cordon in Manchester Getty Images Manchester explosion in pictures Flowers left close to the Manchester Arena, the morning after a suicide bomber killed 22 people, including children, as an explosion tore through fans leaving a pop concert in Manchester Danny Lawson/PA Wire Manchester explosion in pictures Ariana Grande concert attendees Karen Moore and her daughter Molly Steed, aged 14, from Derby, leave the Park Inn where they were given refuge after last night's explosion at Manchester Arena Getty Manchester explosion in pictures Signs saying 'We love Manchester' are displayed in a window in Manchester, England Getty Images

“Despite the clear risk we were faced with, the decision was made to allow three members of staff into the foyer where the blast had taken place.

“The first clinician was on scene within four minutes of the 999 emergency call being allocated and the other two clinicians followed.

“Their job was to triage the injured and work with police to move people to a place close by where they could be treated safely - and where 25 paramedics were waiting, in accordance with our major incident plan.

“Within an hour all critical patients had been moved and were being treated by 50 paramedics. Some people had already been taken to hospital. Within four hours, all the injured that required hospital care had been transferred.”

NWAS said it was confident in its response, which followed a pre-existing major incident plan, but would “welcome any findings or lessons learnt” in a review commissioned by authorities in Greater Manchester.

Firefighters, who carry emergency first aid packs, were allegedly not deployed to the arena until one hour and 47 minutes after the explosion.

Greater Manchester Police (GMP) was charged with coordinating the response, according to established procedure for major incidents.

An injured woman is helped by emergency services in Manchester (London News Pictures)

The force did not answer The Independent’s questions on who made the decision not to send more paramedics into the foyer, or why it took so long for the fire brigade to deploy.

Chief Constable Ian Hopkins said: “Greater Manchester Police’s duty on the night of the attack was to preserve life and protect life.

“We deployed immediately to the scene of the attack in order to do this.

“We recognise it is our role in these situations to put ourselves in as much danger as the public and that's what officers and staff did. This was done in a controlled and planned way along with NWAS.

“We will await the outcome of our debriefs and the independent review before commenting further.”

Andy Burnham, the mayor of Greater Manchester, has commissioned an independent review of the response by former senior civil servant Lord Kerslake.

It is looking at “what responding agencies did well on the night…as well as what could have been done better”, with a panel due to deliver its full findings by April 2018.

In an appeal for witnesses to come forward, Lord Kerslake said: “The review needs to understand exactly what happened so that we can learn the lessons of this terrible night.”

The review’s remit includes looking at issues including preparedness, risk assessments for responders and training, the command structure, communication between agencies and the “provision of support to those physically injured”.

Armed police at Manchester Arena after an explosion at the venue during an Ariana Grande gig (Peter Byrne/PA)

Beverley Hughes, the deputy mayor for policing crime, said Greater Manchester Fire and Rescue Service has “conducted its own debrief” on its response to the Manchester Arena attack and is cooperating fully with the Kerslake Review.

She added: “We have encouraged all staff including, in particular, operational crew across the organisation to contribute information openly through the independent channels provided by the review.

“The review panel will meet with crew to hear their views around the response and this will be organised independently of GMFRS. It would be inappropriate for us to comment further whilst the review is ongoing.”

The Home Office has commissioned former terror law reviewer David Anderson QC to undertake a separate review into the run-up to this year’s terror attacks in Manchester and London.

He will be reviewing internal investigations by MI6 and counter-terror police to look at what was known about the attackers and the risk assessments undertaken before their atrocities.

A Libyan militia holding Abedi’s brother, Hashem, is considering a request to extradite him to the UK to face possible charges of murder, attempted murder and conspiracy to cause an explosion.

British police have pieced together Salman’s movements as he constructed the bomb at properties around Manchester in the days leading up to the bombing.

Experts told The Independent that Salman could have made a lethal quantity of the explosive used in just 24 hours but that direct training or experience would have sped up the process.