Police have arrested three more men in connection with the suicide bombing in Manchester Monday night that killed at least 22 people and left dozens more injured.

The Greater Manchester Police said they apprehended three individuals in south Manchester early Wednesday morning. The arrests come just hours after authorities identified the bomber as 22-year-old Salman Abedi and arrested another 23-year-old man in connection with the attack.

British Prime Minister Theresa May raised the country’s threat level to critical Tuesday, saying another attack could be “imminent.”

“It is a possibility we cannot ignore that there is a wider group of individuals linked to this attack,” May said. “It is now concluded, on the basis of today’s investigations, that the threat level should be increased for the time being — from ‘severe’ to ‘critical.'” (RELATED: Trump Says Those Who Committed Manchester Attack Are ‘Evil Losers’)

“This means that their assessment is not only that an attack remains highly likely, but that an attack may be imminent.”

Members of armed forces to be deployed across the UK as terror level raised – PM Theresa May https://t.co/I7YngSds2C pic.twitter.com/x9t9t1PRTs — BBC Breaking News (@BBCBreaking) May 23, 2017

ISIS has claimed responsibility for the bombing, which killed at least 22 people, including an eight-year-old girl, and injured nearly 60 more. The explosion went off just minutes after Ariana Grande had finished her performance Monday night.

Police are treating it “as a terrorist incident.”