LONDON - British police said 19 people have been confirmed dead, with around 50 others injured after reports of an explosion at Manchester Arena on Monday (May 22), where US singer Ariana Grande had been performing.
The latest statement added that they are currently treating it as a "terrorist incident until police know otherwise".
Police said they responded to calls just before 10.35pm (local time).
Reports said several young girls were among the dead, but this has not been confirmed by authorities.
Initial signs point to a suicide bomber as the cause of the blast, two US officials who spoke on condition of anonymity told Reuters.
Ambulances were seen rushing to the Manchester Arena venue and police added in an earlier statement that people should avoid the area.
"Emergency services responding to serious incident at Manchester Arena," Greater Manchester Police said.
In another update, Police said they carried out a "precautionary controlled explosion" in Cathedral gardens but confirmed that it was abandoned clothing. This followed reports that a suspected device was found.
Several media outlets reported that there had been two explosions from within the venue.
APPALLING TERRORIST ATTACK: THERESA MAY
British Prime Minister Theresa May condemned the "appalling terrorist attack".
"We are working to establish the full details of what is being treated by the police as an appalling terrorist attack," May said in a statement.
She is set to hold a meeting of the country's top security committee at 9am (0800 GMT).
Reports said her campaign for the general election is being suspended.
Mayor of London Sadiq Khan, sharing the earlier police statement in a twitter post, said that the English capital stands with Manchester.
A witness who was at the venue in the northern English city of Manchester where US singer Ariana Grande had been performing said she felt a massive explosion as she was leaving the concert.
"We were making our way out and when we were right by the door there was a massive explosion and everybody was screaming," Catherine Macfarlane told Reuters.
"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."
Witnesses told the BBC that people were being "crushed on the floor" as they scrambled for the exit at the arena.
Robert Tempkin, 22, from Middlesbrough, told the BBC: "Everyone was screaming and running, there were coats and people's phones on the floor. People just dropped everything.
"Some people were screaming they'd seen blood but other people were saying it was balloons busting or a speaker had been popped.
"There were lots of ambulances. I saw somebody being treated. I couldn't tell what had happened to him."
ARIANA GRANDE 'OKAY'
A video posted on Twitter showed fans screaming and running inside the venue.
A spokesman for Ariana Grande said the singer "is okay".
A statement from Manchester Arena confirmed the incident took place outside its venue and as people were leaving the concert.
Manchester Arena, the largest indoor arena in Europe, opened in 1995 and has a capacity for 21,000 people, according to its website. It is a popular concert and sporting venue.
The first unconfirmed reports of an explosion emerged shortly after 2145 GMT.
Suzy Mitchell, whose flat is opposite the venue said: "(I) just heard a huge bang from my bed, came out to the front of my apartment and everyone was running away in big crowds."
Train services to and from Manchester Victoria Station - located under the Arena - had been cancelled.
Britain is on its second-highest alert level of "severe" meaning an attack by militants is considered highly likely.