As many as 22 people have been killed and another 59 injured in the explosion that hit Manchester Arena, the Guardian reported citing police sources.
According to law enforcement agencies, there are children among those killed.
The terror attack was carried out by one man who had brought an improvised explosive device, British police said on Tuesday.
“We have been treating this as a terrorist incident and we believe, at this stage, the attack last night was conducted by one man,” Manchester Chief Constable Ian Hopkins said.
“The priority is to establish whether he was acting alone or as part of a network,” he said. “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.”
The explosion rocked the indoor arena in the English city of Manchester at 22:35 local time (21:35 GMT) right after a concert by American pop singer Ariana Grande. Authorities say the explosion has been treated as a terrorist attack.