MANCHESTER, Englan (CBS) — Britain’s prime minister has raised the country’s terror threat from severe to critical following Monday night’s deadly terror attack at Manchester Arena.

Prime Minister Theresa May says that since the terror threat has been raised, the military will replace police at some public events.

“Our values will always prevail over the hateful ideologies of the terrorists,” May said.

Manchester Terror Attack: 22 Dead At Ariana Grande Concert Blast

The blast following the Ariana Grande concert is the deadliest terror attack on British soil since the 2005 London bombings.

British authorities have identified the suicide bomber as 22-year-old Salman Abedi, but gave no other details.

The Islamic State of Iraq and Syria has claimed responsibility for the carnage, though it remains unclear if they are actually responsible.

British police raided two sites in Manchester in connection with the bombing and a 23-year-old man was arrested at a third location.

Hundreds gathered outside Manchester’s City Hall to honor the young victims of the attack.

The bomb exploded shortly after Grande had left the stage and set off a wave of panic as concert-goers tried to rush out.

“Everyone is pushing, everyone is shoving, there’s shoes being lost, phones being dropped,” said Stephanie Hill.

“It was just smoke and embers falling down from the roof. We just ran and ran,” said Sebastian Diaz. “Girls were crying and we saw these women being treated by paramedics, they had open wounds on their legs.

The explosion killed 22 people, including 12 children under the age of 16. Eighteen-year-old Georgina Callender had met Grande a year ago. Eight-year-old Saffie Roussos is the youngest known victim.

Pennsylvania Company Manages UK Arena Where Terror Attack Took Place

May visited the injured at a children’s hospital.

Authorities say the suicide bomber attacked as crowds left the stadium.

They say Abedi arrived at the venue by train then detonated his explosives near one of the main entrances.

“Our priority is to continue to establish if he was acting alone or as part of a wider network,” said Chief Constable Ian Hopkins.

Manchester police raided the suicide bomber’s home, blowing down his front door before entering. They also arrested an unidentified 23-year-old man.

Several groups held moments of silence for the victims, including the royal family, Manchester’s soccer team and the United Nations.

CBS News has confirmed Abedi was known to British authorities prior to the attack.