Manchester Arena blast: How it happened?

MANCHESTER: At least 19 people were killed and 50 injured in an explosion at Manchester Arena, where 23-year-old American singer Ariana Grande was performing in a concert.

In a statement issued early morning, the Greater Manchester Police said it is "being treated as a terrorist incident until police know otherwise".

—This story has been updated in real-time.

Update [7:50 AM PST]: Singer Ariana Grande, who left just before the blast at her concert, has expressed her condolence, saying that she is "so so sorry. i don't have words",

Update [7:40 AM PST]: British Prime Minister Theresa May is set to hold a meeting of top national security committee members at 9 AM (1 PM Pakistan time) on Tuesday, broadcaster Sky News said.

May has also suspended her general election campaign, Telegraph reported.

Update [7:30 AM PST]: The US Department of Homeland Security mentioned it was closely monitoring the situation in Manchester, England, adding it had "no information to indicate a specific credible threat involving music venues in the United States."

"However, the public may experience increased security in and around public places and events as officials take additional precautions," the Department's statement said.

Update [7:15 AM PST]: "The injured are being treated at six hospitals across Greater Manchester," Chief Constable Ian Hopkins of GM Police explained in a statement issued early morning.

The police official further stated, "We are working closely with the national counter terrorism policing network and UK intelligence network," stressing that people should "remain vigilant".

Update [7:05 AM PST]: In a Twitter statement, Canadian Prime Minister Justin Trudeau expressed Canadians' shock "by the news of the horrific attack in Manchester tonight".

Update [7:00 AM PST]: A number for those impacted by the Manchester Arena incident has been set up.

Nicola Sturgeon, the Scottish First Minister, commented on the "Heartbreaking news from Manchester".

Nigel Farage also tweeted.

Update [6:30 AM PST]: Initial signs point to a suicide bomber as the cause of a blast, two US officials who spoke on condition of anonymity said.

Update [6:20 AM PST]: British politicians have started releasing their statements on the horrific Manchester Arena blast.

May has said her thoughts are with the victims and families of those affected in "what is being treated by the police as an appalling terrorist attack", Express UK reported.

Labour Party leader Jeremy Corbyn said, "My thoughts are with all those affected and our brilliant emergency services."

Liberal Democrat leader Tim Farron also tweeted a message.

On the other hand, US House of Representatives Speaker Paul Ryan stated that he is "praying for the victims and their families".

Other celebrities joined in to express solidarity.

Update [6:00 AM PST]: A Twitter user tweeted photos of those who have been reported missing and others who have been found.

Update [5:49 AM PST]: The GM police officers engaged in the "precautionary controlled explosion in Cathedral Garden confirm that it was abandoned clothing, not a suspicious item", GM Police said on Twitter.

Update [5:35 AM PST]: The GM Police, in an update, said they intend to carry out "a controlled explosion in Cathedral gardens shortly if you hearing anything don't be concerned".

Update [5:15 AM PST]: The GM Police has released fresh information pertaining to the Manchester Arena blast.

Update [5:12 AM PST]: Speculations surrounding the blast indicate that a 'nail bomb' was used, Geo News reported.

Update [5:10 AM PST]: American media is terming the incident as a "terrorist act", Geo News reported.

Update [5:00 AM PST]: The North West Counter Terrorism Unit is treating the incident in Manchester as a possible terrorist incident, sources said.

Senior national Counter-Terrorism officers are assembling in London and are liaising with the Home Office.

Investigative teams and British Police have cordoned off a one-mile-radius area. In addition, a taxi service is offering free rides to those affected to facilitate commuting from the scene.

"London stands with Manchester", stated Mayor of London Sadiq Khan on his Twitter.

Geo News reporters were refused to enter the area, while police refrained from making any comments to them.

Update [4:45 AM PST]: A bomb disposal squad has reached the site of the explosion.

The Oxford Circus venue nearby has also been evacuated.

Update [4:30 AM PST]: According to unconfirmed reports from unofficial sources, as many as 25 people are dead, while over 100 have been injured.

Note that the police have only confirmed fatalities in the incident, but not provided a number yet.

Update [4:21 AM PST]: Helicopters have been summoned to the site for additional medical assistance. British police have termed it a "serious incident".

"We were making our way out and when we were right by the door there was a massive explosion and everybody was screaming," concert-goer 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."

Update [4:10 AM PST]: More than 50 ambulances are currently present at the site.

Update [4:02 AM PST]: The GM Police says "there are a number of confirmed fatalities".

Update [3:35 AM PST]: A spokesman for Ariana Grande's record label said the singer was "okay".

Update [3:32 AM PST]: The area around Manchester Arena has been cordoned off, with security authorities asking people to "stay away" from the area. Ambulances and emergency teams rushing to the site.

Update [3:31 AM PST]: Some people on social media say the blast may be a balloon at the venue.

Update [3:30 AM PST]: Unconfirmed reports indicate a man has been apprehended while trying to escape during the stampede, Geo News reported.

Update [3:25 AM PST]: Services at the Victoria Park Railway Station have been suspended following the incident.

Initial report [3:20 AM PST]: Reports of a blast at Manchester Arena, UK, surfaced late Monday night, with Greater Manchester Police confirming "an incident".

American singer Ariana Grande was performing at Manchester Arena, a venue in the northern English city.

Police have issued a warning to "stay away from the area", following two blasts that led to a stampede, with almost 15,000-20,000 attendees trying to escape.

Videos from the site surfaced social media.

Another video clip has emerged that, by chance, recorded the sound of the blast.

Most of the nearby arenas have also been evacuated. It is noteworthy that most of the locality has residential apartments and student hostels.

Celebrities also started issuing comments on social media.

"Manchester Arena, the largest indoor arena in Europe, opened in 1995 and has a capacity for 21,000 people, according to its website.

People present at the event included those who had come in from other parts of Europe.

(Editorial note: Content shared by users on social media has not been independently verified)

—Additional reporting by Tanveer Khatana and Ghulam Mustafa Mughal; editing by Haseem uz Zaman