According to the AP:

LONDON (AP) — An explosion struck an Ariana Grande concert in northern England late Monday, killing at least 19 people and injuring dozens in what police say they are treating as a terrorist attack.

Greater Manchester Police said 19 people were confirmed dead and roughly 50 were injured by the explosion at Manchester Arena. Emergency vehicles were helping the injured and bomb disposal units were later seen outside the venue.

There was mass panic after the explosion at the end of the concert, which was part of Grande’s The Dangerous Woman Tour.

Britain’s terrorist threat level has been set at “severe” in recent years indicating an attack is highly likely.

Witnesses reported hearing two loud bangs coming from near the arena’s bars at about 10:35 p.m. but there were few further details.

“A huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena,” concertgoer Majid Khan, 22, 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 towards us as they were trying to exit.”

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

Video from inside the arena showed concertgoers screaming as they made their way out amid a sea of pink balloons.

I was there. It was awful to witness and I'm in shock that 20 people have sadly lost their lives 😢😢😢 #Manchester pic.twitter.com/MfTilHqgUg

— Zach Bruce (@Zach_Bruce) May 22, 2017

https://twitter.com/hannawwh/status/866775833553379328

Dashcam video appears to catch explosion at Manchester Arena https://t.co/t4cJUUCHAo pic.twitter.com/c96G7jEOwI

— Fox News (@FoxNews) May 23, 2017

Many of those injured in reported Manchester Arena explosion have "shrapnel injuries," @SkyNews reports https://t.co/2vnMEne0IE pic.twitter.com/66pytHhFav

— CBS News (@CBSNews) May 23, 2017

https://twitter.com/TRobinsonNewEra/status/866805165520760833

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

UPDATE:

Official: Male at scene identified as probable suicide bomber at Manchester Arena. https://t.co/5oMFtElczX https://t.co/YmwP7mVkd4

— Anderson Cooper 360° (@AC360) May 23, 2017

NBC News: UK law enforcement officials and US officials briefed on the investigation say that there's been a tentative ID on the bomber.

— Tom Winter (@Tom_Winter) May 23, 2017

FOX NEWS ALERT: At least 22 killed, 59 injured in #ManchesterBombing at Ariana Grande concert pic.twitter.com/Wzy6DQez4K

— FOX & friends (@foxandfriends) May 23, 2017

FOX NEWS ALERT: 18-year-old Georgina Callander first identified victim of #ManchesterBombing https://t.co/qcbnsYUhaM pic.twitter.com/jX8yCzqGXE

— FOX & friends (@foxandfriends) May 23, 2017

We had to pull nails out of Kids faces. Homeless man sleeping near Arena rushed to help victims. #ManchesterBombing pic.twitter.com/nsaN4N8j7P

— E (@DevotedTroubler) May 23, 2017