Greater Manchester Police have said 22 people died and 59 have been injured by an explosion at the Manchester Arena last night.
The death toll rose this morning from 19 to 22 and children are among the dead.
The attacker also died in the explosion.
The blast is the worst terrorism incident in the UK since the Islamist suicide bombings on London Underground trains and a bus in 2005, which killed 52.
Witnesses described hearing a “huge bang” just after 10.30pm shortly after a concert by US singer Ariana Grande.
Ian Hopkins, chief constable of Greater Manchester police, confirmed on Tuesday that attack was a suicide bombing:
The attacker, I can confirm, died at the arena. We believe the attacker was carrying an improvised explosive device which he detonated, causing this atrocity.
Andy Burnham, mayor of Greater Manchester said:
It is hard to believe what has happened here in the last few hours and to put into words the shock hurt and anger that we feel today. These were children, young people and their families who those responsible chose to terrorise and kill. This was an evil act.
Prime minister Theresa May will attend an emergency meeting of the cabinet emergency Cobra committee this morning. Last night she said that it appeared to be an “appalling attack”.
Campaigning ahead of the general election next month has been suspend by all parties.
May said overnight:
“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.”
Jeremy Corbyn, the Labour leader, said: “Terrible incident in Manchester. My thoughts are with all those affected and our brilliant emergency services.”
Tim Farron, the Lib Dem leader, called off a trip to Gibraltar, saying:
This is a shocking and horrific attack targeting children and young people who were simply enjoying a concert.
Nicola Sturgeon postponed the SNP manifesto launch planned for today, saying: “Heartbreaking news from Manchester. My thoughts are with all those who have lost loved ones or been injured in this barbaric attack.”
Meanwhile, London police have closed London’s Victoria Coach Station this morning and the surrounding streets after finding a suspect package.
“A suspect package is being checked out,” a Metropolitan police spokesman said.
Buckingham Palace Road and other streets in the area are closed, it was reported by the BBC.