By Jill Lawless and Gregory Katz

Associated Press

MANCHESTER, England (AP) — The Islamic State group claimed responsibility Tuesday for the suicide bombing at an Ariana Grande concert in Manchester that left 22 people dead and sparked a stampede of young concertgoers, some still wearing the American pop star’s trademark kitten ears and holding pink balloons.

Teenage screams filled Manchester Arena just after the explosion Monday night, and members of the audience tumbled over guardrails and each other to escape.

An 8-year-old girl was among the dead — the youngest known victim — and the child’s mother and sister were among 59 people wounded in what British Prime Minister Theresa May called “a callous terrorist attack.” The wounded included 12 children under 16.

“We struggle to comprehend the warped and twisted mind that sees a room packed with young children not as a scene to cherish but as an opportunity for carnage,” May said as campaigning for Britain’s June 8 national election was suspended.

May and police said the bomber died in the attack — something that went unmentioned in Islamic State’s claim of responsibility, which gave no name for the attacker. British police announced Tuesday they had arrested a 23-year-old man in connection with the bombing and raided two locations, carrying out a controlled explosion at one of them.

The attack was the deadliest in Britain since four suicide bombers killed 52 London commuters on subway trains and a bus in July 2005.

The attack sparked a nightlong search for loved-ones — parents for the children they had accompanied or had been waiting to pick up, and friends for each other after groups were scattered by the blast. Twitter and Facebook lit up with heartbreaking appeals for the missing.

Some concert-goers said security was haphazard before the show, with some people being searched and others allowed inside unhindered. The bombing took place at the end of the concert, when the audience was streaming toward the exits of Manchester Arena, one of the largest indoor concert venues in the world.

Witnesses said the blast scattered bolts and other bits of metal, indicating the bomb may have contained shrapnel intended to maximize injuries and deaths.

“There was this massive bang. And then everyone just went really quiet. And that’s when the screaming started,” said 25-year-old Ryan Molloy. “As we came outside to Victoria Station, there were just people all over the floor covered in blood. My partner was helping to try to stem the blood from this one person … they were pouring blood from their leg. It was just awful.”

As police shut down public transport, Manchester residents opened their hearts. Taxis offered to give stranded people free rides home while some residents opened their homes to provide lodging.

Grande, who was not injured in the blast, tweeted hours later: “broken. from the bottom of my heart, i am so so sorry. i don’t have words.”