A suicide bomber has killed 22 people - including children - in an explosion that tore through fans leaving an Ariana Grande pop concert in Manchester. At least 59 people were also injured in the blast, which was caused by an improvised explosive device carried by the attacker, at the Manchester Arena on Monday night. Victims described being thrown by the blast, which scattered nuts and bolts across the floor, and told of seeing smoke and smelling burning in the foyer area. Explosion rocks Ariana Grande concert in Manchester, in pictures It is the worst terror attack to hit Britain since the July 2005 suicide bomb attacks in central London in which 52 people were killed and came four years to the day Lee Rigby was murdered by Islamist extremists. Police were called to reports of an explosion at 10.33pm, shortly after Grande, the US singer, had finished her performance as thousands of people streamed out of the Arena. More than 240 calls were made to the emergency services, with responders including 60 ambulances flooding the area and more than 400 police officers deployed as part of the operation. Announcing that the death toll had risen and that children are among the dead, Greater Manchester Police chief constable Ian Hopkins said: "This has been the most horrific incident we have had to face in Greater Manchester and one that we all hoped we would never see. "Families and many young people were out to enjoy a concert at the Manchester Arena and have lost their lives." Mr Hopkins said investigators believed the attack was conducted by one man who died at the scene, although detectives are working to establish if he "was acting alone or as part of a network".