MANCHESTER: At least 19 people have been killed and 50 injured after a reported explosion hit Manchester Arena following a concert by US singer Ariana Grande.

Greater Manchester Police in a statement said the incident is "being treated as a terrorist incident until police know otherwise".

?This is a developing story and will be updated as more information is received. Please stay tuned.

Update [5:15 AM PST]: Greater Manchester 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.

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]: Greater Manchester Police says "there are a number of confirmed fatalities".

Update [3:35 AM PST]: A spokesman for Ariana Grande's record label said that 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.

Britain is on its second-highest alert level of "severe" meaning an attack by militants is considered highly likely. On the other hand, major, nearby arenas have also been evacuated.

An unconfirmed number of people have been injured, sources revealed. Most of the locality has residential apartments and student hostels.

"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.

?Additional reporting by Tanveer Khatana and Ghulam Mustafa Mughal (on site); editing by Haseem uz Zaman

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