Witnesses have described carnage and chaos in the northern English city of Manchester following an apparent terror attack at a concert by US pop star Ariana Grande.
Police have confirmed that at least 22 people have been killed and 59 injured in an explosion at Manchester Arena on Monday night, 10:33 pm local time (7:33 am AEST).
The blast appears to have occurred shortly after Ariana Grande left the stage and people were starting to exit the arena.
"Broken," the 23-year-old tweeted. "From the bottom of my heart, I am so sorry, I don't have words."
Parents and friends have been searching frantically for missing loved ones, posting photos of missing teenagers online. Local venues have opened their doors to stranded concertgoers as hospitals attempt to manage a chaotic situation.
Accounts from within the venue describe chaotic scenes as a loud bang sent people running for the exits after the show.
A video on social media shows a single flash near the arena followed by a loud boom. The venue has tweeted that the incident took place outside the arena, "in a public space".
A man speaking to the BBC said he had been blown "about 30 foot" by the blast while he was waiting to pick up his wife and daughter.
He said that panic erupted as families rushed to find loved ones in the chaos.
"It's shocking what happened. Just carnage everywhere. There was a good 20 to 30 of them [victims]. Some were young kids, some were disabled people," the man said.
"When I got up and looked around there was about 30 people scattered everywhere, some of them looked dead, they might of been unconscious but there was a lot of fatalities.
"My first thing was to run in the stadium to try and find my wife and daughter."
When he couldn't find them in the stadium, he rushed back outside and began checking bodies. He eventually found his wife and daughter alive and well by the arena.
What we know:
In a widely shared but unverified post on Facebook, a teenager from North Lanarkshire shared photos of her hair and belongings covered in blood and debris from the explosion.
"As we were leaving a bomb or explosion went off meters in front of me," she wrote.
"That sound, the blood and those who were running around clueless with body parts and bits of skin missing will not be leaving my mind anytime soon, or the minds of those involved."
Concertgoer Majid Khan, 22, told The Independent she heard what sounded like a "huge bomb-like bang". Robert Tempkin, 22, that people dropped everything and ran in panic.
"Everyone was screaming and running, there were coats and people's phones on the floor," he said.
"Some people were screaming they'd seen blood but other people were saying it was balloons busting or a speaker had been popped," Mr Tempkin said.
"There were lots of ambulances. I saw somebody being treated. I couldn't tell what had happened to him."
Police have asked the public to avoid the area around the arena.
Bomb disposal teams conducted a controlled explosion in Cathedral Gardens, 200 meters from the venue, but have confirmed the item appeared to be abandoned clothing.
Chaos as people flee Manchester Arena
Ms Khan, who says she was inside the venue when the explosion occurred, told The Independent the bang sent people running.
An exit near her was blocked, she said, "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," she said.
A representative for Grande told Reuters the 23-year-old singer is "okay" after the incident.
In a video which appears to have been taken after most people had fled from the arena, an announcer can be heard urging everyone to remain calm.
“Thank you for coming and having a good time tonight, everything is fine," a voice says over a PA system.
“Ladies and gentlemen please take your time, there’s no need to bunch up, there’s no problems here, just take your time and keep exiting the building.”
Six hospitals nearby are dealing with injured casualties. An NHS representative said things were "very chaotic".
British Prime Minister Theresa May and Opposition Labour Leader Jeremy Corbyn have both expressed their sympathies. The current election campaign is expected to be suspended in the wake of the attack.
"All our thoughts are with the victims and the families of those who have been affected," the Prime Minister said in a statement.
"Terrible incident in Manchester," Corbyn said on Twitter. "My thoughts are with all those affected and our brilliant emergency services."
Australians with concerns about the welfare of family and friends in Manchester should attempt to contact them directly. If you are unable to contact them, you should call the Department of Foreign Affairs and Trade’s 24-hour Consular Emergency Centre on: 1300 555 135 (option 6) or +61 2 6261 3305 if overseas.
A local hotline established by authorities in the UK is also available on: 0161 856 9400
A flash followed by a loud boom outside the venue
Blast sparks panic in Manchester Arena
- with AAP
