(CNN) — Charlotte Campbell was praying her 15-year-old daughter was alive.
Olivia and her friend Adam were missing after attending an Ariana Grande concert in Manchester Arena on Monday night, Campbell said.
“She was enjoying herself and we’ve not heard anything from her since,” Campbell said. “We’ve phoned hospitals, we’ve phoned everywhere we can think. We’ve posted on every social network and there’s nothing.”
Some witnesses described scenes of panic and carnage following a blast outside the arena, which left at least 22 people dead and 50 injured. There were bodies and blood everywhere, and smoke filled a corridor and a stairway. Frantic parents called out for their children.
Andy James, a witness, said he heard an explosion and ran out of the arena with 9-year-old brother in his arms. Screaming fans streamed out of the arena along with him.
“The sound rattled my chest,” James said. “I looked up and saw everyone start to scream and run back down the stairs.”
It was the first concert that James’ brother had been to. The tickets were an early birthday present, James said. The concert had just finished when the chaos started.
“The stewards were trying to calm people down but everyone was running in a stampede,” recalled James, who made his way out of the arena through another exit. James said he believed he heard a second explosion as they were running out.
His brother’s heart was “beating out of his chest,” he said.
Police described the blast as a possible terrorist incident. “This is currently being treated as a terrorist incident until police know otherwise,” Greater Manchester police said on Twitter.
“There was just bodies scattered about everywhere … it was just chaos,” Kiera Dawber said 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.”
The crowd was made up of mainly young people who had come to see Grande in her first of three scheduled concerts in the United Kingdom, on her European and Latin American tour.
“There was a lot of little girls running out, and parents shouting out and yelling names,” Delgado said.
‘The roads were bedlam’
Sam Ward, who lives by the arena, said the loud bang he heard “really nothing like I have ever heard in the city center before.”
He saw ambulances and heard sirens.
“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.