19 confirmed dead after reports of explosion at Ariana Grande concert

UK police: 19 confirmed dead after reports of explosion at Ariana Grande concert

The incident, at Manchester Arena, is being treated as a terrorist incident until police know otherwise, Greater Manchester Police said in a statement.

A representative said Ariana Grande was not injured.

A U.S. law enforcement source who received a preliminary briefing said the situation is fluid but that there were two explosions that contained nails, CBS News investigative producer Pat Milton reports. The source said there are more than 20 casualties, apparently including a large number of young girls.

The source said that one person was detained in a vehicle but it is not clear what, if any, involvement that potential suspect may have had in the incident.

Witnesses reported hearing two loud bangs coming from near the arena's bars.

"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, said, "The bang echoed around the foyer of the arena and people started to run."

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.

"Due to an incident involving the emergency services [Manchester Victoria] has been evacuated," Northern train service officials said. "We will provide further updates when possible."

Joseph Carozza, a representative from Grande's U.S. record label, said Ariana Grande is OK and they are investigating what happened.

Zach Bruce, who was at the concert, described the scene on the phone to CBSN.

"It was one loud bang -- it was so loud," Bruce said.

Asked if he would describe it as an explosion, he said yes -- "It was an explosion."

He described people panicking.

"I didn't know what was going on," he said.

One Twitter user said she heard an "explosion" from inside the area, where Grande performed moments earlier. There were no immediate details of what happened during the concert.

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

One concert goer told BBC 5 she was one of first people to exit the stadium. She said she heard an explosion toward the end of the performance. There were an estimated 20,000 people inside the arena on Monday night.

Jeremy Corbyn, leader of the Labour Party, responded to reports of the incident on Twitter.

"Terrible incident in Manchester," he said. "My thoughts are with all those affected and our brilliant emergency services."

The Dangerous Woman Tour is the third concert tour by Grande to support her third studio album, Dangerous Woman. The tour began on February 3, 2017, in Phoenix, Arizona at the Talking Stick Resort Arena.

From Manchester the tour is to move through Europe, including Belgium, Poland, Germany, Switzerland and France, through the summer with stops in Brazil, Chile, Argentina, Costa Rica, Mexico and on to Japan, Thailand, the Philippines, New Zealand, Australia and more.

This story is developing. Check back for updates.