MANCHESTER, England — Prime Minister Theresa May says Britain's threat level from terrorism has been raised to critical — meaning an attack may be imminent.
May says Salman Abadi, the suicide bomber who killed 22 people at a concert in Manchester, may have been part of a bigger network.
She said Abadi was born and raised in Britain.
The level previously stood at the second-highest rung of "severe" for several years.
May said critical status means armed soldiers may be deployed instead of police at public events such as sports matches.
Survivors of the suicide bombing that killed 22 people at a Manchester concert hall say security screening ahead of the Ariana Grande show was haphazard.
Nikola Trochtova said she was leaving the venue when she heard the explosion. She told Czech radio that there was almost no security screening ahead of the concert.
It is still unclear how the bomber was able to enter the area undetected. The blast happened right after Grande left the stage and the arena lights went back up.
Most of the 130 people killed in the November 2015 attacks on multiple Paris venues were attending a show at the Bataclan concert hall.
Pre-event security protocols vary country by country and according to venues. Security experts say one protective measure that could have been taken was extending the security perimeter around the Manchester arena.
Former U.N. secretary-general Kofi Annan says the world must stand together against "the extremists and terrorists" responsible for the attack in Manchester and similar senseless violence elsewhere.
Annan told The Associated Press on Tuesday that all countries need to work together and share information to deny extremists "their opportunities" and bring those who commit crimes to justice.
Annan now leads the group of former world leaders founded by Nelson Mandela called The Elders.
Speaking on behalf of the group, he said it's "tragic that young people who have gone to listen to music and dance should be cut down so brutally and senselessly."
Annan said: "Terrorists have been around, but they've always lost, and they will lose this time, too. It may take time, but they will lose."