A lone male suicide bomber was behind the terror attack that killed more than 20 people during an Ariana Grande concert at Manchester Arena, police have said.
Police raised the death toll to 22 and said children were among those killed.
A total of 59 people were left injured in the blast.
Greater Manchester Police chief constable Ian Hopkins, confirmed the attack was carried out by one man although at this stage police do not know if the bomber "acted alone or was part of a wider network".
He said the attacker, who died at the scene, was carrying an improvised explosive device which he detonated.
Mr 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.
"Our thoughts are with those 22 victims that we now know have died, the 59 people who have been injured and their loved ones.
"We continue to do all we can to support them."
Witnesses reported hearing a "huge bomb-like bang" at around 10.30pm on Monday, as fans were leaving the arena shortly after a show by Ariana Grande finished, and described glass and metal nuts on the floor.
Some witnesses described seeing smoke and smelling burning in the foyer area of the arena.
The Prime Minister has condemned the "appalling" incident and General Election campaigning has been suspended.
A Government's emergency Cobra committee is expected to take place at around 9am on Tuesday morning chaired by Theresa May, Downing Street said.
The attack is the worst carried out in the UK since 56 people were killed in the 7 July London bombings in 2005.
Victims of the explosion are being treated at eight hospitals across the city of Manchester.
The Manchester attack comes after four people died in March following an attack on Westminster in London, which targeted the Houses of Parliament.
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