- 22 killed, at least 59 injured after blasts at end of Ariana Grande teen concert in Manchester.
- Attack conducted by one man, who was carrying a device which he detonated.
- Islamic State has reportedly claimed responsibility for the attack.
- A 23-year-old man has been arrested in Manchester in connection to the attack.
- Most victims believed to be teens; video shows panicked young fans fleeing venue in tears.
- First victim named locally as 18-year-old Georgina Callander.
- Second victim named as eight-year-old Saffie Rose Roussos.
- BBC reports the Northwest Counter Terrorism Unit is treating the blast as terrorism.
- Witnesses describe "carnage everywhere" at conclusion of concert.
- Ariana Grande tweets "from the bottom of my heart, I am so so sorry. I don't have words".
- World leaders react, with President Trump condemning the "evil losers" behind the blast.
The suicide bomber who killed 22 people and injured 59 more at the Manchester Arena has been named as 22-year-old Salman Abedi.
Abedi was named by Greater Manchester Chief Constable Ian Hopkins, according to the Daily Telegraph.
"I can confirm that the man suspected of carrying out last night's atrocity has been named as 22-year-old Salman Abedi. However, he has not yet been formally identified and I wouldn't wish, therefore, to comment further."
"The priority remains to establish whether he was acting alone or as part of a network."
The Islamic State group has claimed responsibility for the suicide bombing.
The group said one of its members carried out the attack, according to the Associated Press.
Earlier British police arrested a different man in connection with the bombing, which happened at the end of an Ariana Grande concert.
A 23-year-old man was arrested by armed police in Chorlton, Manchester. The BBC said more arrests and raids were expected to follow.
Prime Minister Theresa May addressed the public tonight, telling a grieving United Kingdom that security services believed they had identified the attacker, who is thought to have acted alone. But authorities were still trying to ascertain whether he was part of a wider network.
The suicide bomber's name is yet to be released but one of victims has now been named as 18-year-old Georgina Callander.
She is one of at least 22 people who died when a nail bomb was detonated on Monday night UK time about 10.30pm outside an Ariana Grande concert at the Manchester Arena. At least 59 people were wounded in the attack, and many of the dead were children.
The injured were taken to eight hospitals around Manchester, including 12 children under 16 who were taken to the Royal Manchester Children's Hospital.
May will head to Manchester tonight (NZ time) to meet with emergency services, Chief Constable Ian Hopkins and the city's mayor Andy Burnham. She will also chair another high level cabinet office security meeting, convened during times of emergency.
May said the terrorist attack was among the worst Britain had experienced and many of the 59 hospitalised had life-threatening injuries.
The attacker deliberately chose "the time and place to cause maximum carnage and to kill and injure indiscriminately".
"All acts of terrorism are cowardly attacks on innocent people but this attack stands out for its appalling, sickening cowardice - deliberately targeting innocent defenceless children and young people who should have been enjoying one of the most memorable nights of their lives.
"We struggle to comprehend the warped and twisted mind that a sees room of young people as an opportunity for carnage," May said.
Queen Elizabeth issued a statement saying: "The whole nation has been shocked by the death and injury in Manchester last night of so many people, adults and children."
The bomb exploded at the end of Grande's teen concert as she was making her way off stage.
Witnesses have also told of nuts and bolts tearing into young concert-goers when the blast was detonated in the foyer area between the arena and the next-door Victoria station just after the Ariana Grande gig ended.
Chief Constable Ian Hopkins, who is heading the investigation, said more than 400 officers have been involved in the operation during the night.
"This is a fast-moving investigation and we have significant resources deployed to both the investigation and the visible patrols that people will see across Greater Manchester as they wake up to news of the events last night," he said.
"We have been treating this as a terrorist incident and we believe that while 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."
Police have confirmed the attacker died at the arena and was carrying an improvised explosive device, which he detonated.
"Our priority is to work with the national counter-terrorist policing network and UK intelligence services to establish more details about the individual who carried out this attack," Hopkins said.
"This has been the most horrific incident we have had to face in Greater Manchester and one that we all hoped we would never see.
"Families and many young people were out to enjoy a concert at the Manchester Arena and have lost their lives."
The injured were being treated at eight hospitals across Greater Manchester.
Horrifying footage showed petrified children leaping over chairs and barriers as they desperately tried to escape the 21,000-seat venue, which led to a stampede.
Armed officers surrounded the venue and bloodied casualties were seen being stretchered out of the concert that resembled a "war zone".
Ariana Grande tweeted her heartbreak in the hours after the explosion.
"I am so so sorry. I don't have words."
Earlier today police carried out a controlled explosion at Cathedral Gardens after finding a second suspicious device.
Forensic evidence, including a body, suggests the explosive device was detonated by a suicide bomber, according to a briefing from UK to US officials. The device is believed to have been packed with nails.
Video footage showed people fleeing in tears from the venue after bangs rang out immediately after the concert finished.
Bloodied concertgoers were pictured being helped by emergency services outside the gig and armed police were seen patrolling the arena.
Video footage showed people fleeing in tears from the venue after reports of explosions at the end of the concert, according to the Daily Mail.
Evie Brewster, who attended the concert, told MailOnline: "Ariana Grande had just finished her last song and left the stage when a huge explosion sounded.
"Suddenly everybody started screaming and running for the exit.
"We could hear the police and ambulance sirens. It was terrifying.
"There were thousands of people trying to get out at once. They were all screaming and crying. The whole place smelled smokey and burned.
"The explosion sounded like it was inside the building somewhere."
Manchester's Victoria station, which backs onto the arena, has been evacuated and all trains cancelled.
Jonathan Yates, 24, from the Wirral, who attended the gig, told MailOnline: "The concert had finished and the lights came on almost instantly. There was a bang, a weird bang. There were lots of balloons but I thought to myself that can't be a balloon, that's not normal.
"We were on the floor level and it came from the higher seats, people were running and screaming. Everyone stopped and I turned to my friend and said 'we need to run'. Everyone was running and screaming and then when we got out it felt a bit more okay.
"I heard five or six bangs that sounded like gunshots. When we got outside people were outside, crying and on their phones.
"You don't think it's something that's going to happen when you go. It was such a nice, fun concert."
Nick Schurok, 28, from Manchester, told MailOnline: "Ariana Grande had just finished the concert and the lights came on. Everyone started leaving. I was on the floor and at the back of the arena people started exiting through the tunnels.
"There was a bang in the left tunnel and everyone went to the middle tunnel. Then about two minutes later, there was another bang. The bang was so loud and crowds of people were running. There were lots of children and families there."
Another witness Jenny Brewster told MailOnline: "We were exiting the building when it happened. We'd headed towards the main doors as Ariana was performing the last song because we wanted to beat the crowds, but as we made our way there a wall of security men blocked it and told us to go the other way.
"Seconds later they shouted 'run!' and the explosion happened right behind them. Hundreds of people were running and screaming. Those men saved our lives."
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."
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 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 while this had gone off, so it was just extremely disturbing for everyone there."
Another concert-goer Laura, 22, told MailOnline: "There was a woman leaning against a car in the car park with her head down, covered in blood and a little girl being lifted away by paramedics. There were quite a few people injured in the car park."
Her friend, Livvy, 22, added: "We saw the explosion happen. Bits of it hit me. My first thought was, 'that's a bomb'.
"It was just when we were leaving. We saw a flash of light and smoke.
"We're really shaken up. If we had been there moment earlier we would have been caught up in it rather than seeing it."
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."
Suzy Mitchell, 26, whose flat is opposite the area, 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.
"Lots of emergency services going to and from. But can't see anything substantial as of yet except fleeing people and lots of cars.
Former Manchester United footballer Rio Ferdinand said: "Just heard the news what's happening in Manchester. Hope everyone is safe and sound!"
- additional reporting: Daily Mail, AAP