At least 59 casualties have been treated at hospitals in the Manchester area following an explosion at an Ariana Grande concert on Monday night.

The North West Ambulance Service NHS Trust have confirmed that they treated ''a number of walking wounded'' at the scene as well as over 50 in hospitals across the city.

They wrote on their official Twitter page: ''NWAS has taken 59 casualties from the Manchester Arena incident to various hospitals & treated a number of walking wounded on scene.''

Greater Manchester Police's Chief Constable Ian Hopkins appeared outside the force's headquarters to make a brief statement. He said the wounded were being treated at six hospitals across Manchester, before adding: ''We are currently treating this as terrorist incident until we have further information. It is important that people avoid the area around Manchester Arena.''

It had previously been reported that at least 19 people had died following the ''explosion''.

In a statement on Twitter, police said: ''Further details on the incident at Manchester Arena have now been released. 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.''

And a statement by the British Transport Police said the explosion happened ''within the foyer area''.

It reads: ''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.

''Please avoid the area whilst emergency services continue to respond to this incident. No trains or trams are running from Manchester Victoria station.''