MANCHESTER — At least 22 people, including some children, were killed after a reported explosion at an Ariana Grande concert in Manchester, England on Monday night (May 22), police have confirmed.

Another 59 people were injured at the Manchester Arena.

Manchester Chief Constable Ian Hopkins says the attacker died in the explosion.

"We believe, at this stage, the attack last night was conducted by one man.

"The priority is to establish whether he was acting alone or as part of a network.

"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." 

Witnesses reported hearing a huge bang at the venue, Sky News said on Monday. Initial signs point to a suicide bomber as the cause of the blast, two US officials who spoke on condition of anonymity, told Reuters.

"This does not appear to have been a carefully planned attack involving multiple actors, extensive surveillance of the target or exotic materials.

"That is what is so worrisome about this kind of thing - how simple it is to indiscriminately kill, wound and terrorise innocent people. With our partners, the US has begun the process of combing through the available intelligence to see if anything was missed," said a US official.

The Manchester Arena tweeted that the incident had taken place outside the venue in a public space as fans were leaving.

Witness at Manchester Arena describes scenes of "chaos" as people rushed to leave after "huge bang" https://t.co/Iz9PCxvlJr pic.twitter.com/i2YMBRldJK

pic.twitter.com/cPwkQbrYp2

A video posted on Twitter showed fans screaming and running inside the venue.

EXPLOSION AT MANCHESTER ARENA AND EVERYONE RAN OUT SO SCARY pic.twitter.com/pJbUBoELtE

BREAKING NEWS: MULTIPLE FATALITIES AFTER REPORTED EXPLOSION AT ARIANA GRANDE CONCERT IN MANCHESTER. pic.twitter.com/IEsD7pu2Xo — Kevin W. (@kwilli1046) May 22, 2017

"Ariana is OK," said her publicist, Joseph Carozza. "We are further investigating what happened."

A few hours after the incident, Grande tweeted that she was "broken".

"From the bottom of my heart, i am so so sorry. i don't have words," she wrote.

Authorities are treating the case as a possible terrorist incident, reports the BBC. British Prime Minister Theresa May said authorities were working to establish the details of the blast.

"We are working to establish the full details of what is being treated by the police as an appalling terrorist attack," she said in a statement.

"All our thoughts are with the victims and the families of those who have been affected."

If confirmed as a terrorism incident, it would be the deadliest attack in Britain by militants since four British Muslims killed 52 people in suicide bombings on London's transport system in July 2005.

The blast occurred on the anniversary of the murder of soldier Lee Rigby, who was hacked to death on a London street on May 22, 2013. Rigby's gruesome murder gained international notoriety when Michael Adebolajo was filmed by passers-by standing in the street with blood-soaked hands trying to justify the attack.

The blast also came two and half weeks ahead of an election in which Prime Minister Theresa May is predicted by opinion polls to win a large majority. 

No militant group has claimed responsibility so far but Islamic State supporters celebrated on social media. Twitter accounts affiliated to the militant Islamist group have used hashtags referring to the blast to post celebratory messages, with some users encouraging similar attacks elsewhere.

The incident caused train services to Manchester to be disrupted, according to National Rail, and Manchester Victoria station was evacuated with trains unable to run.

One concertgoer, 22-year-old Majid Khan, told The Independent: "I and my sister, along with a lot of others were seeing Ariana Grande perform at Manchester Arena, and we were all exiting the venue when around 10.40-10.45pm-ish, a huge bomb-like bang went off that hugely panicked everyone and we were all trying to flee the arena.

"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 Trinity Way and that was blocked so everyone was just running to any exit they could find as quickly as they could.

"Everyone was in a huge state of panic, calling each other as some had gone to the toilet whilst this had gone off, so it was just extremely disturbing for everyone there."

Another concert go-er Catherine Macfarlane told Reuters: "We were making our way out and when we were right by the door there was a massive explosion and everybody was screaming,"

"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 of the area."

One concertgoer, Sasina Akhtar, told The Manchester Evening News that there had been an explosion at the back of the arena after the last song. "We saw young girls with blood on them," she said. "Everyone was screaming, and people were running."

Parents separated from their children during the mayhem were told to go to a Holiday Inn, where many children had taken refuge. Local residents offered stranded concertgoers places to stay in their homes.

Gary Walker, who was at the show with his wife and two daughters, said he "heard a massive bang and saw a flash" just as the concert finished. He turned and realized that his wife had been hurt. Walker, who is from the northern city of Leeds, said she had a stomach wound and possibly a broken leg. He said he lay down with her and saw "metal nuts on the floor."

His wife was taken to a hospital, and Walker was standing with his daughters at Deansgate, the main shopping street in Manchester.

The confusion and fear in the hours afterward was reflected on social media. One Twitter post asked: "Did anybody see my girlfriend? I lost her in the chaos."

The BBC interviewed one witness who was waiting outside the arena to pick up his wife and daughter. He recounted that the "whole building shook," that there was "carnage everywhere," and that the explosion appeared to come from near the stadium's ticket area.

Britain is on its second-highest alert level of "severe" meaning an attack by militants is considered highly likely.

British counter-terrorism police have said they are making on average an arrest every day in connection with suspected terrorism.

In March, a British-born convert to Islam ploughed a car into pedestrians on London's Westminster Bridge, killing four people, before stabbing to death a police officer who was on the grounds of parliament. He was shot dead at the scene.

The Singapore Ministry of Foreign Affairs (MFA) said there were no reports of Singaporeans directly affected or injured in the incident.

"MFA and the Singapore High Commission in London have reached out to Singaporeans who are e-registered in Manchester... The Singapore High Commission will work closely with the Manchester Police to monitor the situation closely."

"Singapore strongly condemns the bomb attack at the Manchester Arena on 23 May 2017 that resulted in numerous deaths and injuries of innocent people.  We express our deepest condolences to the bereaved families, and wish the injured a swift recovery," the MFA's statement added. AGENCIES

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