MANCHESTER, England — Investigators hunted Tuesday for possible accomplices of the suicide bomber who attacked an Ariana Grande concert in Manchester, killing 22 people and sparking a stampede of young concertgoers, some still wearing the American pop star’s trademark kitten ears and holding pink balloons.

The Islamic State group claimed responsibility for the Monday night carnage, which also left 59 people wounded, though a top American intelligence official said the claim could not be verified. British police raided two sites in the northern English city and arrested a 23-year-old man at a third location.

British Prime Minister Theresa May and police said the bomber died in the attack on Manchester Arena — a detail that was not included in the Islamic State claim, which also had discrepancies with the events described by British officials.

Manchester police chief Ian Hopkins identified the bombing suspect as 22-year-old Salman Abedi but gave no other details.

A European security official, speaking on condition of anonymity because he was not authorized to speak about the ongoing investigation, said Abedi was a Briton of Libyan descent. British election rolls listed him as living at a modest red brick semi-detached house in a mixed suburb of Manchester where police performed a controlled explosion Tuesday afternoon.

Neighbor Natalie Daley said she was frightened by a loud bang, then police yelling, “Get in your houses — get away from the windows!”

“When it’s like two seconds from your house, when you walk past it every day, you do live in fear,” Daley said.

Manchester, 160 miles (260 kilometers) northwest of London, is one of Britain’s largest cities and Manchester Arena is one of the world’s largest indoor concert venues.

Campaigning for Britain’s June 8 national election was suspended in the aftermath of the attack, the deadliest in Britain since four suicide bombers killed 52 London commuters on subway trains and a bus in July 2005.

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

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.

An 8-year-old girl was among the dead — the youngest known victim — and her mother and sister were among the wounded in what May called “a callous terrorist attack.” The wounded included 12 children under age 16, hospital officials said.

“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.