Update: British Prime Minister Theresa May said U.K. officials believe another terror attack is imminent, so the country is increasing the threat level from severe to critical. This means armed soldiers could potentially be deployed and substitute police officers at public events.
May also believes Salman Abadi, the 22-year-old man identified as the suspected suicide bomber by the authorities, may have belonged to a bigger network.
Update May 23, 2017, 5 a.m.: The death toll from last night's Ariana Grande concert explosion has risen to 22, The Guardian reports. Another 59 people were injured in the attack, which police are investigating as a suicide bombing. Officials also confirmed that children were among the dead.
"Tonight, our hearts are broken," Braun, who also represents Justin Bieber, wrote. "Words cannot express our sorrow for the victims and families harmed in this senseless attack.
"We mourn the lives of children and loved ones taken by this cowardly act. We are thankful for the selfless service tonight of Manchester's first responders who rushed towards danger to help save lives. We ask all of you to hold the victims, their families, and all those affected in your hearts and prayers."
Update: Ariana Grande has responded to the tragedy at Manchester Arena on Twitter.
Original story follows.
Emergency crews arrived at the scene after the blasts, which were first reported about 10:40 p.m. (5:40 p.m. ET), NBC News reported. It was not immediately clear what kind of explosion occurred, and sources stressed that “information was preliminary and subject to change.”
U.K. Prime Minister Theresa May said in a statement that the British Home Office is "working to establish the full details of what is being treated by the police as an appalling terrorist attack," according to ABC News.
A video on social media from inside the arena shows attendees screaming while fleeing the concert.
Officials told NBC News the blast took place as the concert ended, “catching people as they exited.” A least one blast took place in the foyer of the arena, not the main event hall, the Times reported citing the British Transport Police.
A number of the casualties might have been caused by a stampede of people fleeing the venue, according to NBC News.
”Ariana is O.K.,” her publicist told the Times. “We are further investigating what happened.”
Another concert-goer told The Manchester Evening News there was a blast at the back of the arena after the final song. “We saw young girls with blood on them, everyone was screaming and people were running,” Sasina Akhtar said.
Eyewitness Karen Ford told the BBC, "The lights had come up everyone was just getting out and walking towards the stairs, when all of a sudden this huge sound which sounded like an explosion went off."
People took to social media to find loved ones after getting separated amid the chaos after the incident. It appears that two friends who attended the concert were able to find each other thanks to Twitter:
Grande, 23, is currently on an international tour supporting her 2016 album, “Dangerous Woman.” The tour was scheduled to continue on Thursday at the O2 Arena in London.
Check back for updates this breaking news story.