Nineteen people have died after a blast tore through a pop concert at Manchester Arena in a suspected terror attack, police have said.

Greater Manchester Police said that around 50 other people were injured in the explosion at the Ariana Grande concert.

The force said in a statement: "This is currently being treated as a terrorist incident until police know otherwise."

The police update said: "Just before 10.35pm on Monday 22 May 2017, police were called to reports of an explosion at Manchester Arena.

"So far 19 people have been confirmed dead, with around 50 others injured.

"This is currently being treated as a terrorist incident until police know otherwise."

Witnesses reported hearing a "huge bang" at the venue shortly after US singer's gig finished on Monday evening.

The area around the arena was swamped with police and emergency services and approach roads were closed.

One fan at the concert with his sister described how the explosion happened as fans were leaving the arena.

Majid Khan, 22, said: "A huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena.

"It was one bang and essentially everyone from the other side of the arena where the bang was heard from suddenly came running towards us as they were trying to exit."

Oliver Jones, 17, who attended with his 19-year-old sister, said: "The bang echoed around the foyer of the arena and people started to run.

"I seen people running and screaming towards one direction and then many were turning around to run back the other way."

Manchester's Victoria station, which backs on to the arena, has been evacuated and all trains and trams cancelled.

National Rail said: "As Manchester Victoria is located near the arena, the station has been evacuated and all lines closed.

"Trains are currently unable to run to/from Manchester Victoria. Some trains will be cancelled throughout or start/terminate at alternative stations. Disruption is expected to continue until end of the day."

British Transport Police said: "Officers are at Manchester Arena following reports of an explosion within the foyer area of the stadium at 10.30pm this evening.

"Emergency services are at the scene and we are working to establish more information regarding the explosion and will provide further updates as soon as possible."

The ambulance service warned people only to call "for life-threatening emergencies" and said a "large number of resources" were at the incident.

Manchester Arena said the explosion happened "outside the venue in a public space".

"Our thoughts and prayers go out to the victims," it said.

Joseph Carozza, a representative from Grande's US record label, said the singer is okay and they are investigating what happened.