Concert-goers and witnesses have described the chaos after "huge bomb-like bangs" went off in Manchester Arena following an Ariana Grande gig.
One fan at the concert with his sister described how the apparent explosion hit the venue as they were leaving the building.
Majid Khan, 22, said: "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 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."
Oliver Jones, 17, was at the concert with his 19-year-old sister.
He said: "I was in the toilet and heard a loud bang just after the concert had finished and people had started to leave.
"The bang echoed around the foyer of the arena and people started to run.
"I seen people running and screaming towards one direction and then many were turning around to run back the other way.
"Security was running out as well as the fans and concert goers.
"Reports of blood and people injured."
He added: "In so much shock and panic. You see this on the news all the time and never expect it to happen to you. I just had to run and make sure me and my sister were safe."
Footage posted online by one concert-goer shows fans filing out of the building while an announcer attempts to maintain calm.
The voice can be heard saying: "Ladies and gentleman, please take your time, there’s no need to bunch up, there are no problems here - just take your time and keep exiting the building."
A barman at the nearby Steven Charles Snooker Club, who gave his name as Tyler, said he saw people lying on the ground covered in blood.
"We’ve had a few people in with panic attacks and in all kinds of disarray," he told Press Association.
"We’ve got four girls here - trying to get them sorted to get picked up.
"There was a gentleman on the floor with his leg all bleeding and woman with blood down one side of her face.
"We felt something but didn’t know what it was - there was a sound like thunder.
"One girl had a panic attack and another had streaming tears, a woman had a heart attack just outside.
"It’s a lot of teenagers - they’re all in tears."
Suzy Mitchell, 26, whose flat is opposite the venue, reported a huge bang rocking the neighbourhood.
She told the Press Association: "(I) just heard a huge bang from my bed, came out to the front of my apartments (we’re on the top floor so have perfect view) and everyone was running away in big crowds.
"The bang was so big I heard it from my room which is at the back of the apartment blocks.
"Currently lots of emergency services going to and from. But can’t see anything substantial as of yet except fleeing people and lots of cars."
Liverpool City Region metro mayor Steve Rotheram tweeted: "My 2 daughters caught up in the Manchester explosion at the arena. They are thankfully safe, but I fear for others."
He posted later: "Confirmed deaths at the Manchester arena. Feel sick to think that people have lost their lives at a gig attended by so many young people.
"All my thoughts go out to those parents waiting to hear of the safety of their children. It’s a parents worse nightmare. So, so sad."
A woman who said she worked at the arena as staff but did not want to be named said: "All I know is it sounded like a bomb."
Another concert-goer, a woman with her husband and three young children, said as the concert ended here was a loud bang and everyone leaving the venue then rushed back in.
She said: "I just freaked. Everyone started screaming. We did not see any explosion but it smelt bad, like burning."
Several people on the streets who had been to the gig were visibly upset and in tears and did not want to speak.
A family from Newcastle said they were missing two family members and had been unable to contact them.
A middle-aged woman said her partner, aged 32, and daughter, 19, were outside the arena to pick up her younger daughter who attended the concert.
She said: "There was a bang, a massive explosion". They have not been seen or heard of since and are not answering their phones.
Another man who took his daughter to the gig said: "Ariana said: ’Bye bye Manchester!’ The lights came on then there was two big noises and people started running and shouting.
"We got in a lift to go up to the next floor to the exits. When the doors opened I saw blood on the floor and two injured people. Blood all over their faces. A lot of people were in shock."