Twenty two people have been killed and about 59 injured in a suspected terror attack at Manchester Arena.
Police were called to reports of an explosion at the venue at about 22:35 BST following a pop concert by the US singer Ariana Grande.
The cause of the blast is unknown but North West Counter Terrorism unit is treating it as a possible terrorist incident, sources have told the BBC.
Greater Manchester Police is working to set up a contact number for relatives.
Officers have told the BBC there is a second suspect device near where the first explosion occurred.
Reporters were moved away from the scene and a controlled explosion has taken place.
BBC Home Affairs Correspondent Daniel Sandford said senior counter-terrorism officers were assembling in London and liaising with the Home Office.
British Transport Police say the explosion was in the foyer area of Manchester Arena.
Manchester Victoria station, which is close to the concert venue, has been closed and all trains cancelled. (BBC)