Police in Manchester, U.K., say at least 19 people are dead and 59 injured following reports of an explosion at Manchester Arena, where American singer Ariana Grande performed Monday night.

鈥淲e are currently treating this as a terrorist incident until we know otherwise,鈥� Greater Manchester Police Chief Constable Ian Hopkins told reporters.

Emergency response personnel and bomb disposal units have been sent to the scene.

"We are working to establish the full details of what is being treated by the police as an appalling terrorist attack," British Prime Minister Theresa May said in a statement.

"All our thoughts are with the victims and the families of those who have been affected."

Few other details were immediately available, but people in the area have reported hearing loud bangs coming from near the arena's foyer at approximately 10:35 p.m.

The bangs were reportedly heard after the conclusion of Grande鈥檚 performance. Video shot inside the arena shows concertgoers screaming as they rush towards the venue鈥檚 exits.

A representative for the singer has reported that Grande is safe. The pop star tweeted her condolences several hours after the explosion.

A Twitter account dedicated to posting photos and videos of Grande captured a large boom heard inside the venue.

鈥淥h my God! What is going on? What just happened,鈥� said a panicked woman in the 19-second clip. Screams erupted through the crowd as hordes of fans abandoned their seats.

Some Twitter users have posted pictures of friends and family believed to be at the event in an effort to determine if they are among the dead or injured.

"A huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena," 22-year-old Majid Khan, who was at the concert, 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."

Prime Minister Justin Trudeau said he was 鈥渟hocked by the news of the horrific attack鈥� in at tweet late Monday.

 

With files from The Associated Press