MANCHESTER, England — An explosion struck outside an Ariana Grande concert at the Manchester Arena late Monday night, killing at least 22 people and injuring about 50 others in what police say they are treating as a terrorist attack.
“This is currently being treated as a terrorist incident until police know otherwise,” Manchester police said on Twitter.
“We can confirm there was an incident as people were leaving the Ariana Grande show last night. The incident took place outside the venue in a public space. Our thoughts and prayers go out to the victims,” police said early Tuesday on Twitter.
After the initial incident, police carried out a precautionary controlled explosion nearby but the item turned out to be discarded clothing, not a "suspicious item," Greater Manchester Police said.
Investigators are looking into the possibility of a suicide bombing outside of the arena, according to a Western law enforcement official and a U.S. law enforcement official.
The explosion rocked the area at about 10:33 p.m. Monday in Manchester.
Video from near the scene showed a caravan of ambulances heading to the arena.
Joseph Carozza, a representative from Grande's U.S. record label, said the singer is OK and they are investigating what happened. The singer later tweeted:
"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."
British Prime Minister Theresa May said the government is working to establish "the full details of what is being treated by the police as an appalling terrorist attack."
She said her thoughts are with the victims and the families of those who have been affected. The government is expected to call an emergency Cabinet meeting.
If the incident is confirmed as a terrorist attack it would be the most deadly in Britain since the London subway bombings in 2005.
In Washington, the U.S. Department of Homeland Security said, "At this time, we have no information to indicate a specific credible threat involving music venues in the United States. However, the public may experience increased security in and around public places and events as officials take additional precautions."
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.
Ivo Delgado, a witness, told CNN he heard one explosion. He said there was smoke in a main corridor outside the arena seating and stage area..
"It was a really big explosion. Everybody started screaming and running," he said.
Delgago said: "There were people on the floor ... There was a lot of confusion."
In a Facebook post, Greater Manchester Police released the following statement:
"Emergency services are currently responding to reports of an explosion at Manchester Arena. There are a number of confirmed fatalities and others injured. Please AVOID the area as first responders work tirelessly at the scene. Details of a casualty bureau will follow as soon as available."
British Transport Police told CNN it was in the process of closing some transport in the area.
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.