Police first warned people to stay away from Manchester Arena in northern England following reports of two loud bangs in the area following a concert. 

Greater Manchester Police later tweeted that they were responding to a "serious incident" at the arena. 

A concert by pop singer Ariana Grande had just finished at the arena when the loud bangs were reportedly heard. A representative for the pop star told Variety she is "okay".

There are reports the loud bangs, which some described as sounding like gunshots or explosions, could have been part of the act. 

Emergency services are at the scene. 

Oliver Jones, 17, was at the concert with his 19-year-old sister.

He told PA: "I was in the toilet and heard a loud bang just after the concert had finished and people had started to leave.

"The bang echoed around the foyer of the arena and people started to run.

"I seen people running and screaming towards one direction and then many were turning around to run back the other way.

"Security was running out as well as the fans and concert goers.

"Reports of blood and people injured."

He added: "In so much shock and panic. You see this on the news all the time and never expect it to happen to you. I just had to run and make sure me and my sister were safe."