MANCHESTER, England -- At least 22 people were killed and 59 others are injured after reports of an explosion after an Ariana Grande concert at England's Manchester Arena on Monday, British police confirmed.
Police responded to reports of an explosion at the arena where Grande was performing around 10:35 p.m. local time. The audience included many children.
"We are currently treating this as a terrorist incident until we know otherwise," Chief Constable Ian Hopkins of the Greater Manchester Police said. "We are working closely with the national counter terrorism policing network and U.K. intelligence partners."
The U.S. Department of Homeland Security said there are no credible threats to music venues in the United States.
"At this time, we have no information to indicate a specific credible threat involving music venues in the United States," the statement said. "However, the public may experience increased security in and around public places and events as officials take additional precautions."
A representative for Grande told Billboard that the 23-year-old singer is OK after the incident. Grande tweeted that she was "broken" following the attack.
Videos from inside the arena showed the concertgoers, which included many children, running from the building while overhead announcements can be heard telling fans to "stay calm."
"It was a really big explosion. Everybody started screaming and running," concertgoer 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."
Manchester Arena is the largest indoor arena in Europe and has a capacity of 21,000 people, according to its website.
It was the first of three scheduled shows in the U.K. for Grande's "Dangerous Woman Tour."
Grande was originally scheduled to perform at The O2 Arena in London on Thursday and Friday, but those shows, along with the remainder of her European tour, have been "indefinitely suspended," according to TMZ.