An explosion struck an Ariana Grande concert in Manchester, UK late Monday (22 May), killing at least 22 people and injuring dozens in what police say they are treating as a terrorist attack. Greater Manchester Police revised the death toll from 19 to 22 early Tuesday morning.

The force’s chief constable, Ian Hopkins, said Tuesday they believe one person carried out the attack. Police are trying to determine if the person acted alone or had support in the Monday night blast.

Police say some 400 officers were deployed overnight to help with the investigation.

Emergency vehicles were helping the injured and bomb disposal units were later seen outside the venue.

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.

Greater Manchester Police say they are working with national police and intelligence agencies in what is being treated as a terrorist incident.

“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.

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 cancelled.

A controlled explosion of another “suspect device” happened after police moved to the show.

The arena has a capacity of 21,000. Manchester transport police said the explosion occurred in the foyer of the arena.

If it is confirmed as terrorism, this attack will have been the deadliest terror attack in the United Kingdom since the London subway bombings of 7 July, 2005 that killed 52.

Ariana Grande tweeted that she was “broken”. And “from the bottom of (her) heart” that she was “so sorry” and did not have words.

“When we got out they just said ‘Keep on running, keep on running.'”

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

Campaigning was suspended in Britain’s national election with Prime Minister Theresa May cancelling campaign events on Tuesday after the blast. She is due to chair a meeting of the government’s emergency committee, COBRA, at 9h local time.

Liberal Democrat leader Tim Farron cancelled a campaign tour to Gibraltar after the explosion.

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 US record label, said the singer is OK and they are investigating what happened.

Canadian Pubic Safety Minister Ralph Goodale said his thoughts and prayers are with the victims and their families and all Canadians “stand firm” with the British people.

Ottawa is advising Canadians in the UK to avoid the affected area in Manchester.

Canadians there are also being advised to contact Global Affairs if they require emergency assistance.

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.

Statement by European Commission President Jean-Claude Juncker following the attacks in Manchester

"It was with great sadness and profound shock that I learnt of the brutal attack that struck Manchester.

"It breaks my heart to think that, once again, terrorism has sought to instil fear where there should be joy, to sow division where young people and families should be coming together in celebration.

"I would like to convey my deepest sympathies to Prime Minister May and to the British people.

"Today we mourn with you. Tomorrow we will work side by side with you to fight back against those who seek to destroy our way of life. They underestimate ours and your resilience – these cowardly attacks will only strengthen our commitment to work together to defeat the perpetrators of such vile acts."

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