Twenty two people have died after a blast tore through crowds leaving a pop concert at Manchester Arena in a suspected terror attack.

Witnesses reported hearing a "huge bang" at the venue during a sold-out Ariana Grande gig on Monday evening.

GMP's Chief Constable Ian Hopkins said it is being treated as a terrorist incident. It is believed that the attack was carried out by one man.

CLICK HERE FOR LIVE UPDATES: 22 dead after terrorist attack at Manchester Arena 

High school pupil missing after Manchester terrorist attack

Video from the scene of the police cordon this morning in Salford:-

If found to be a terrorist attack it would the worst atrocity in the UK since 56 people were killed in the 7/7 London bombings in 2005.

An emergency number for those who are concerned about loved ones or anyone who may have been in the area has been issued - 0161 856 9400.

Casualties are being treated at eight hospitals across Greater Manchester.

The Bolton News:

British Transport Police said the explosion happened within the foyer area of the stadium at about 10.30pm. 

Witnesses reported scenes of panic, confusion and smoke inside the building. 

Police had earlier said there were already a "number of confirmed fatalities and others injured" and emergency services at the scene after "reports of an explosion".

A Facebook post, by Paula Robinson from Westhoughton, is being shared online in a bid to reunite lost children with their families.

Dawn Price, from Bolton, was at the concert with her daughter and their friends. 

She said: "I'm really shaken and can't process what happened as so many people were there with children.

"There was a big bang just as it finished and everyone started to run back into the arena.

"Then seconds later people started to run back in from another exit."

The Bolton News:

Picture taken with permission from the twitter feed of @Zach_bruce of people running through Manchester Victoria Station

The area around the arena was swamped with police and emergency services. Approach roads have been closed by police.

Witnesses said they heard two loud bangs inside the arena and coming from where the bars are located.

Manchester's Victoria Station, which backs onto the arena, has been evacuated and all trains cancelled.

One fan at the concert described how the explosion hit the venue as fans 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 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.

The Bolton News:

"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."

A British Transport Police statement said: "Officers are at Manchester Arena following reports of an explosion within the foyer area of the stadium at 10.30pm this evening.

Emergency services are at the scene and we are working to establish more information regarding the explosion and will provide further updates as soon as possible." 

Concert-goers and witnesses described the chaos after "huge bomb-like bangs" went off.

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 saw 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."

The Bolton News:

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."

The Bolton News:

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."

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."

Theresa May said her thoughts were with the victims and families of those affected in the Manchester incident, which is being treated as an "appalling terrorist attack".

The Prime Minister said the authorities were working to establish what happened at the Manchester Arena.

Mrs May said: "We are working to establish the full details of what is being treated by the police as an appalling terrorist attack.

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

She will chair a meeting of the Government's emergency committee Cobra to respond to the suspected Manchester terror attack.

A Tory source said the Prime Minister's General Election campaign was being suspended.

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."

Mr Rotheram thanked the taxi driver who picked up his two girls from the venue.

Witnesses reported helicopters were circling above the scene after reports of the blast.

Armed police swamped the streets around the arena and police were moving members of the public away from the area.

Just after 1.30am police said: "There will be a controlled explosion in Cathedral Gardens shortly if you hearing anything don't be concerned."

Police later said 'abandoned clothing, not a suspicious item'.

Labour leader Jeremy Corbyn said his thoughts were with all those affected by the "terrible incident" in Manchester following a reported explosion at a packed concert.

His political rival Tim Farron, the Liberal Democrat leader, condemned the "shocking and horrific" attack targeting youngsters at the concert.

In a message on Twitter Mr Corbyn said: "Terrible incident in Manchester. My thoughts are with all those affected and our brilliant emergency services."

Mr Farron said: "This is a shocking and horrific attack targeting children and young people who were simply enjoying a concert.

"My deepest sympathies are with the victims, and with families who have lost loved ones, as well as those desperately waiting for news.

"I would like to pay tribute to the bravery and dedication of the emergency services.

"This is an attack on innocent people and the nation is united both in its grief and its determination to stand up to this deplorable attack."

Labour's Lucy Powell, who is hoping to retain the Manchester Central seat, said she had spoken to Greater Manchester mayor Andy Burnham about the incident.

"This is a major incident targeted at our city," she said. "Our hearts go out to all and our gratitude to emergency services."

It is thought about 20,000 people were attending the US singer's concert at the arena, many children and teenagers. 

The 23-year-old US pop singer, who found fame as the child star of Nickelodeon series Victorious, was touring the world when tragedy struck.

In a statement released through her manager, Scooter Braun, Ariana said she was heartbroken by the event.

The Bolton News:

"Tonight, our hearts are broken. Words cannot express our sorrow for the victims and families harmed in this senseless attack," the statement read.

"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."

The Dangerous Woman Tour started in Phoenix, Arizona, on February 3 and she was joined by British pop stars Little Mix during a spell in the US.

She then made stops in Dublin, Sweden, Norway, Denmark and the Netherlands.

After Manchester she was due to play two nights in London's O2 Arena before visiting Poland, Germany, Switzerland, France, Spain and Italy.

The world of music has been sending messages of support after the incident.

A Manchester Arena statement said: "We can confirm there was an incident as people were leaving the Ariana Grande show.

"The incident took place outside the venue in a public space.

"Our thoughts and prayers go out to the victims."

National Rail said: "As Manchester Victoria is located near the arena, the station has been evacuated and all lines closed.

"Trains are currently unable to run to/from Manchester Victoria. Some trains will be cancelled throughout or start/terminate at alternative stations. Disruption is expected to continue until end of the day."

How terror unfolded at the Manchester Arena 

Monday, 6pm: Doors open at Manchester Arena in the city centre. US pop singer Ariana Grande is on the bill for a sell-out concert at the 21,000-capacity venue. Fans, many of them teenage girls, excitedly share selfies as they wait for the show to begin.

7.30pm: Show's scheduled start time. After a performance from support act BIA, an American rapper, Grande takes the stage.

10.30pm Show's scheduled finish. Thousands of fans begin to file out of the arena's four exits.

A "huge bomb-like bang" is heard at the arena. Witnesses describe being knocked from their feet by an explosion and seeing dozens of injured, possibly dead, people including children lying on the floor. Others describe panic as concert-goers run for exits.

10.35pm: GMP are called to reports of an explosion at Manchester Arena. Dozens of emergency services vehicles stream into the area.

10.55pm: Police urge people to stay away from the area as responders deal with a "serious incident".

11.46pm: Police say there have been a number of confirmed fatalities.

Tuesday, 1.10am: Nineteen people are confirmed dead and around 50 others injured following the suspected explosion police say is being treated as a terrorist incident.

1.30am: A controlled explosion is carried out on a suspicious item in the Cathedral Gardens area near Manchester Arena. It is later confirmed to be abandoned clothing.

2.15am Prime Minister Theresa May says her thoughts are with the victims and families of those affected in "what is being treated by the police as an appalling terrorist attack".