The cause is still unknown but the police are reportedly treating it as a terrorist attack until they know otherwise. They are working closely with the national counter-terrorism policing network and UK intelligence partners.
According to Reuters, US officials suspected that the attack was carried out by a suicide bomber.
The explosion reportedly occurred at the foyer shortly after 10.30pm at the arena which can hold up to 21,000 people.
A majority of the audience at the concert were children and teenagers.
One of the concertgoers, Chris Pawley recorded the chaos that ensued following the tragedy.
@ManchesterArena So Scary! pic.twitter.com/4EoDNgR6bJ
— Chris Pawley (@ChrisPawley1) May 22, 2017
Manchester Victoria station located just under the arena was reportedly shut down after the blast and all train services were stopped temporarily.
The police had reportedly performed a precautionary controlled explosion on a suspect device at the nearby Cathedral gardens. It turned out to be a false alarm.
Hours following reports of the incident, locals in Manchester started sharing #RoomForManchester on social media offering assistance to those who were stranded in the city.
Meanwhile, Grande’s publicist told reporters that she is “okay”.
The singer is currently on an European tour. She previously performed in Birmingham and Dublin prior to Manchester and was due to play in London later this week.