(Ellie Cheetham/Twitter via Storyful)

The final lines of the star’s provocative pop anthem, “Dangerous Woman,” still rang in Stacey Brown’s ears. It was her first Ariana Grande concert, a surprise for her 11th birthday.

She had traveled here Monday from Aberdeen, Scotland, with her parents. The concert, she said, had fulfilled her wildest dreams — “the songs, the background, the stage, the lights. It was all so good.”

The 23-year-old singer left the stage, and the lights came up. Concertgoers reached for their bags and coats as others made an early start for the doors, including Stacey and her mother, Sharon Moir, 43.

A bang was heard.

(The Washington Post)

“There was silence for like three seconds, then someone screamed,” recalled Mark Harrison, who had brought his 12-year-old daughter, Arin, to the concert from Cumbria, in northern England.

It was the beginning of a night of panic and carnage, as a homemade explosive detonated in the entrance hall of the Manchester Arena, one of the world’s largest indoor venues, with a capacity of 21,000. The bombing, in which the attacker himself was killed, was the deadliest terrorist strike in Britain since 2005.

Twenty-two concertgoers died, and dozens more were injured. On Tuesday, the Islamic State asserted responsibility, though similar claims after past attacks have not been proved.

Eyewitness accounts, police statements, photos and video footage paint a grisly scene of chaos and gore, in which the glee of music fans — many of them teenagers, some younger still — turned to horror.

A recording from inside the concert hall captures the moment the bomb detonated, leading to gasps and, seconds later, screams. Disbelief and confusion reigned. “Oh my God,” a woman exclaimed. Audience members scanned the arena. Suddenly sensing danger, they darted from the aisles.

As they fled, some parents assured their children that the noise had just been the popping of a balloon. Or an equipment malfunction. Or pyrotechnics.

Forensic officers investigate the scene near the Manchester Arena on Tuesday, a day after a suicide attack at an Ariana Grande concert left 22 people dead. (Kirsty Wigglesworth/AP)

“Stick together — let’s get out, get out,” Heidi Hemblys, 43, told her two young daughters. They followed a train of people through a fire exit. She saw one man clutching his head, tears streaming down his cheeks, after he saw bodies dismembered by the blast in the arena’s foyer.

“We heard people say it was a bomb, and so I couldn’t lie to my kids,” Hemblys said. “It was supposed to be a fun night. It’s absolutely terrifying.”

More than 240 calls came in for emergency services beginning at 10:33 p.m. Monday, according to the Manchester police. Immediately, the police presence in the Victoria train station, which adjoins the concert hall, was immense, said Moir, who rushed to meet her partner on the curb outside. She had to make it through “absolute mayhem” to get there.

“There were people everywhere with cuts, people crying, people trying to call their kids, screaming for their kids,” she said.

By 10:46, emergency health workers were on the scene, said David Ratcliff, director of the ambulance services. Most victims were taken to Royal Manchester Children’s Hospital, said Ratcliff, who estimated that there were more than a dozen children among the injured.

Meanwhile, desperate calls went out on social media from family members and friends of those still missing. “Please just somebody get ahold of her. I’m worried sick,” Charlotte Campbell told the BBC of her daughter, Olivia, 15, who was not answering her phone. “We’ve not slept.”

Those whose young children made it safely home said they were thankful, inexpressibly so, but they wondered how they would explain this sort of violence to them. They feared for their innocence.

“You just don’t want to believe it at first,” said Gina Bhaird, 43, who attended the concert with her 14-year-old son, who is autistic. “Noise affects him, and so that’s why we got up to leave the concert slightly early. He’s going to be in bits now.”

On Tuesday, Stacey Brown’s 11th birthday, she sat white-faced in the lobby of a downtown hotel, getting ready to leave for home. She thought she was going to spend the rest of her life reliving the show, only her second pop concert. Now she was afraid to remember its aftermath.

“I haven’t seen anything like this,” she said, gripping her bag.

James McAuley contributed to this report.