The Manchester concert attack.@breakingnews

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UK PM raises terror threat level to critical 02:42

Manchester, England...The UK raised its terrorism threat level to "critical" -- the highest level -- for the first time in a decade Tuesday. Prime Minister Theresa May warned that intelligence services believe an attack may be "imminent."

Hours earlier, police identified 22-year-old Salman Abedi as the suspected suicide attacker who detonated a bomb as throngs of teenagers poured out of an Ariana Grande concert in Manchester, killing 22 people. Abedi is of Libyan descent, sources in Manchester's Libyan community told CNN. May said he was born and raised in the UK.

The attacker, I can confirm, died at the arena. We believe the attacker was carrying an improvised explosive device, which he detonated, causing this atrocity," said Chief Constable Ian Hopkins.

While police believe the suspect was acting alone, investigations are ongoing to establish if he was part of a network.

As many as 400 police were deployed overnight, Hopkins said early Tuesday. He added that residents should expect to see more armed officers on the streets.

If confirmed as a terror incident, it would be the deadliest attack on British soil since the 2005 London bombings, which killed 52 people.

• Attacker, believed to have been carrying an improvised bomb, also died at the scene.

Key developments

• Ariana Grande suspends her world tour.
• Police have carried out two raids in Manchester.
• Queen Elizabeth II described bombing as "act of barbarity."
• 59 people injured, some in life-threatening situations.
• US President Donald Trump slams attackers as "losers."
• British Prime Minister says police have identified the suspect.

The suspect apparently acted as a lone attacker and died in the blast Monday night, police said, which left the wounded and the dead scattered across the arena's bloodied entrance and sent screaming girls running for cover.

Olivia Campbell, 15, had been confirmed as one of the dead.

Teen concertgoer Olivia Campbell, whose mother spoke to CNN during an agonizing wait for news from her daughter, is the latest victim to have been confirmed dead. Fifteen-year-old Olivia had gone to the concert with her friend Adam to celebrate his birthday.

People tend to the injured inside the Manchester Arena after the attack Monday night.

ISIS said on its Telegram channel Tuesday that a "soldier of the caliphate" was able to "plant explosive devices" at the arena, a US counterterrorism source told CNN. ISIS routinely claims attacks it has no proven connection to.

Authorities have discovered no evidence of a link between the attacker and an established terror group, a British counterterrorism official told CNN. A US counterterrorism official said bombing "looks much like" an ISIS attack but that American intelligence officials were working with British counterparts to determine more.

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