Many of those killed are feared to be children there to watch US pop star Ariana Grande, who had just left stage.
Thousands who had watched the appearance fled after hearing a “massive bang” with crowds of screaming and crying teens rushing from the venue.
Witnesses told how nuts and bolts were sent flying in the blast at the foyer area as fans made their way to Manchester Victoria train station next door.
Prime Minister Theresa May has slammed the “appalling terrorist attack”, which came on the fourth anniversary of the murder of British soldier Lee Rigby. Read more from the source