Scene video: Twitter/Ellie Cheetham via CNN
LONDON (AP) — Greater Manchester Police have raised the death toll in a blast at an Ariana Grande concert to 22.
The force’s chief constable, Ian Hopkins, said Tuesday they believe one person carried out the attack.
“The priority is to establish whether he was acting alone or as part of a network,” Hopkins said. “The attacker, I can confirm, died at the arena. We believe the attacker was carrying an improvised explosive device which he detonated, causing this atrocity.”
Police say some 400 officers were deployed overnight to help with the investigation.
Officials say children are among the victims.
There was mass panic after the explosion at the end of the concert, which was part of Grande’s The Dangerous Woman Tour. The singer was not injured, according to a representative.
Grande posted a brief message on social media following the incident: “broken. from the bottom of my heart, i am so so sorry. i don’t have words.”
Britain’s terrorist threat level has been set at “severe” in recent years indicating an attack is highly likely. Police said the explosion is being judged a terrorist attack unless new information proves otherwise.
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.
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.
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.
Joseph Carozza, a representative from Grande’s U.S. record label, said the singer is OK and they are investigating what happened.
The Dangerous Woman Tour is the third concert tour by Grande and supports her third studio album, “Dangerous Woman.”
Grande’s role as Cat Valentine on Nickelodeon’s high school sitcom “Victorious” propelled her to teen idol status, starting in 2010.
The 23-year-old Grande, with her signature high ponytail, went on to also star in spinoffs that included “iCarly,” as she worked to develop her recording career.
The tour began in Phoenix in February. After Manchester, Grande was to perform at venues in Europe, including Belgium, Poland, Germany, Switzerland and France, with concerts in Latin America and Asia to follow.
Scene video: Twitter @hannawwh via CNN