(Reuters) British Prime Minister Theresa May described a suicide bomb attack that killed 22 people in a crowded concert hall as a sickening act targeting children and young people, and police raided houses in the city of Manchester looking for accomplices.
Islamic State, now being driven from territories in Syria and Iraq by Western-backed armed forces, claimed the attack as revenge against "Crusaders". But Western experts were sceptical, noting it had offered two accounts of the attack partly contradicting each other and the British police version.
In a statement made outside her Downing Street offices after a meeting with security and intelligence chiefs, May said police believed they knew the identity of the bomber.
"All acts of terrorism are cowardly," she said. "But this attack stands out for its appalling sickening cowardice, deliberately targeting innocent, defenceless children and young people who should have been enjoying one of the most memorable nights of their lives."
She said security services were working to see if a wider group was involved in the attack, which fell less than three weeks before a national election.
British police moved quickly, arresting a 23-year-old man in connection with Monday night's bombing, carried out as crowds began leaving a concert given by Ariana Grande, a U.S. singer who attracts a large number of young and teenage fans.