Police say at least 19 people have been killed and another 50 injured after an explosion at the Manchester Arena in northern England, where U.S. pop star Ariana Grande was wrapping up a performance.

Police say they were called around 10:35 p.m. local time following reports of an explosion at the venue, which has a capacity of about 21,000.

They say they are treating it as a “terrorist incident” as they investigate. The explosion took place outside the venue in a public place, according to a statement on the Manchester Arena’s Twitter account.

Latest statement on incident at Manchester Arena pic.twitter.com/BEpLOan3dY

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A witness who attended the concert said she felt a huge blast as she was leaving the arena, which was followed by screaming and a chaotic rush, as thousands of people tried to flee the scene.

“We were making our way out and when we were right by the door, there was a massive explosion and everybody was screaming,” concert-goer Catherine Macfarlane told Reuters. “It was a huge explosion — you could feel it in your chest. It was chaotic. Everybody was running and screaming and just trying to get out.”

Witnesses reported that many children were at the concert.

EXPLOSION AT MANCHESTER ARENA AND EVERYONE RAN OUT SO SCARY😭 pic.twitter.com/pJbUBoELtE

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“A huge bomb-like bang went off — that hugely panicked everyone and we were all trying to flee the arena,” another concert-goer, Majid Khan, told Britain’s Press Association. “It was one bang and essentially everyone from the other side of the arena, where the bang was heard from, suddenly came running toward us as they were trying to exit.”

Added 17-year-old Oliver Jones: “The bang echoed around the foyer of the arena and people started to run.”

Emergency vehicles were on the scene helping the injured and bomb disposal units were later seen outside the venue.

Armed police work at Manchester Arena after reports of an explosion at the venue. (Peter Byrne/Associated Press)

Several witnesses, while speaking to the BBC, reported glass shattering and the whole building shaking from an explosion.

Many described bloodied and injured people, and a panic as concert-goers fled the venue.

U.S. pop star Ariana Grande was wrapping up a concert at the Manchester Arena when an explosion rocked the venue. Many of Grande’s fans are young women and girls. (Chris Pizzello/Invision/Associated Press)

Police advised the public to avoid the area around the arena, and the train station near the arena, Victoria Station, was evacuated and all trains cancelled.

A video posted on Twitter showed fans screaming and running inside the venue.

A spokesperson for the pop singer said: “Ariana is okay. We are further investigating what happened.”

Many of Grande’s fans are young women and girls.

U.K.: explosion at Manchester Arena. Canadians, for emergency assistance; call us (toll-free) 00-800-2326-6831 or [email protected]

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