(CNN) Singer Ariana Grande had just performed her last song, "Dangerous Woman," to delighted fans, and the lights had just come on.

As the crowd began to move, many of them children wearing bunny ears like their idol, eyewitnesses at Monday's concert at the Manchester Arena described a loud, sharp bang, and then chaos broke out.

"Ariana had just finished her last song. We were getting ready to leave the arena and the next minute we heard a mighty bang coming from the left-hand side of the arena," Carole Long, who was at the concert with her 10-year-old daughter Robin, told CNN.

"Everyone went crazy and was running and screaming and trying to get out and jumping over seats. How we weren't crushed to death is amazing. People were just pushing and pushing and pushing. The stewards were screaming at people to get out."

Other witnesses say the sound of what police believe was an improvised explosive device -- detonated by one man who was killed in the blast -- was short and sharp like a gun shot, and then the air was filled with smoke.

Twenty two people have been conformed dead, some of them children, and dozens others injured in the worst terror attack in Britain for 12 years.

The crowd was made up of mainly young people who had come to see Grande in her first of three scheduled concerts in the UK, on her European and Latin American tour.

Police help victims of the attack on Monday night.

Abby Mullen, who had traveled down from Scotland for the gig, posted her recollection of the horrific attack on Facebook from her hotel room.

"I thought we would leave seconds before the last song finished ... to get home quicker instead of waiting longer for a taxi. As we were leaving a bomb or explosion went off meters in front of me", she wrote.

"Peoples skin, blood and faeces where (sic) everywhere including in my hair & on my bag. I'm still finding bits of god knows what in my hair."

Helpers attend to injured people at Manchester Arena on Monday night.

Andy James had taken his nine-year-old brother to what was his first ever pop concert. He said the explosion happened at around 10:40 p.m. as they were walking up the stairs to leave.

"It must have been about 40 feet from where we were. We heard the explosion and the boom rattled in my chest. You could just feel it on the ground.

"We left to go in the opposite direction of where the explosion happened. There was a stampede of people, I was trying to help people up as we were leaving.

James said that as he ushered his little brother out, "I had my hand on his chest and his heart was beating so fast."

The scene outside Manchester Arena on Monday night.

'Bodies scattered'

"There was just bodies scattered about everywhere ... it was just chaos," Kiera Dawber told CNN. "There was at least 20 or 30 people on the floor, some that you could see straight off were just ... just dead."

Dawber said she saw a man holding his wife. "She wasn't in a very good state," Dawber said.

"The injuries I saw ... it didn't look like the sort of injuries that people get from tripping over people in a hurry," said Joel Goodman, a freelance photographer on the scene.

Parents shouting out and yelling names

Ivo Delgado, another witness, recalled hearing one explosion before he saw people running.

"It was more a moment of confusion, but still the bang was really great, really massive," he said. "I saw at least 3 people on the floor injured."

"There was a lot of little girls running out, and parents shouting out and yelling names," Delgado said.

Photos: Deadly explosion at Ariana Grande concert People in Manchester, England, gather in St. Ann's Square on Thursday, May 25. They were observing a national minute of silence to remember the victims of a suicide bombing at an Ariana Grande concert. Hide Caption 1 of 22 Photos: Deadly explosion at Ariana Grande concert Britain's Queen Elizabeth II speaks to 15-year-old Millie Robson and her mother, Marie, during a visit to the Royal Manchester Children's Hospital on May 25. The Queen was visiting those injured in the attack. Hide Caption 2 of 22 Photos: Deadly explosion at Ariana Grande concert A police officer guards a house in Manchester as investigations continued on May 25. Police say a man carrying explosives acted as a lone attacker and died in the blast. Hide Caption 3 of 22 Photos: Deadly explosion at Ariana Grande concert Flowers and tribute messages are left for victims in St. Ann's Square. Hide Caption 4 of 22 Photos: Deadly explosion at Ariana Grande concert A women sheds tears after observing the minute of silence in St. Ann's Square. Hide Caption 5 of 22 Photos: Deadly explosion at Ariana Grande concert A Manchester road is closed off as police raids continued on May 25. Hide Caption 6 of 22 Photos: Deadly explosion at Ariana Grande concert Local residents hold Manchester City and Manchester United soccer jerseys during the national minute of silence. Hide Caption 7 of 22 Photos: Deadly explosion at Ariana Grande concert Police officers deliver flowers to a makeshift memorial in Manchester on Wednesday, May 24. Hide Caption 8 of 22 Photos: Deadly explosion at Ariana Grande concert Women cry after placing flowers in Manchester on May 24. Hide Caption 9 of 22 Photos: Deadly explosion at Ariana Grande concert A forensics team works at the scene of the explosion on Tuesday, May 23. Hide Caption 10 of 22 Photos: Deadly explosion at Ariana Grande concert British Prime Minister Theresa May condemns the "callous terrorist attack" as she delivers a statement in London on May 23. Hide Caption 11 of 22 Photos: Deadly explosion at Ariana Grande concert Police help someone after the attack at Manchester Arena on Monday, May 22. Hide Caption 12 of 22 Photos: Deadly explosion at Ariana Grande concert People gather outside the arena. "We can confirm there was an incident as people were leaving the Ariana Grande show last night," police said on Twitter early on Tuesday. "The incident took place outside the venue in a public space. Our thoughts and prayers go out to the victims." Hide Caption 13 of 22 Photos: Deadly explosion at Ariana Grande concert People receive medical attention at a railway station close to the arena. The incident happened shortly after Grande had left the stage, shortly after 10:30 p.m. (5:30 p.m. ET) according to eyewitnesses. Calvin Welsford, an 18-year-old concertgoer, said that he heard a "loud bang" a couple of minutes after Grande's set had finished. Hide Caption 14 of 22 Photos: Deadly explosion at Ariana Grande concert Paramedics respond to the scene. Hide Caption 15 of 22 Photos: Deadly explosion at Ariana Grande concert Emergency workers and concert attendees gather outside the arena. Hide Caption 16 of 22 Photos: Deadly explosion at Ariana Grande concert People stand by a cordoned-off street close to the arena. Hide Caption 17 of 22 Photos: Deadly explosion at Ariana Grande concert Greater Manchester Police tweeted that emergency services were "responding to (a) serious incident at Manchester Arena. Avoid the area. More details will follow as soon as available." Hide Caption 18 of 22 Photos: Deadly explosion at Ariana Grande concert People are escorted away from the arena. Hide Caption 19 of 22 Photos: Deadly explosion at Ariana Grande concert People sit outside near the arena. The crowd was made up of mainly younger people who had come to see Grande in her first of three scheduled concerts in the UK. Hide Caption 20 of 22 Photos: Deadly explosion at Ariana Grande concert An injured man is helped at the scene. Hide Caption 21 of 22 Photos: Deadly explosion at Ariana Grande concert People hug near armed police who responded to the scene. Hide Caption 22 of 22

Sam Ward, who lives by the arena, said the loud bang sounded "really nothing like I have ever heard in the city center before."

"Initially after the first wave of sirens and the initial evacuation, it was filled with cars. The roads were actually bedlam. People actually going through red lights," he said.

Search for the missing

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Meanwhile the search goes on for those still missing, including Charlotte Campbell's 15-year-old daughter Olivia, who had gone to the concert with her friend Adam to celebrate his birthday.

Campbell had spoken to her daughter just before 10 p.m. but hasn't heard from her since.

"We've tried everything we can. They're telling us to wait by the phones," Campbell told CNN. "Her dad is out looking ... It's the most horrible feeling ever, to know your daughter is there and you don't know whether she's dead or alive.

"I want her home and I want her safe ... I just want her to walk through the door."

Her daughter has been registered as a missing person.