Police have confirmed 19 fatalities after blasts rocked an Ariana Grande performance in the Manchester Arena.

Witnesses reported “loud bangs” at the end of the concert, which has injured around 50 people, police have said.

Videos posted on social media showed hundreds of fans fleeing the arena, while one witness reported she “felt the blast in her chest”.

"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 ABC News.

According to the Greater Manchester Police, several individuals were hurt in the "serious incident".

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

Meanwhile, a spokesperson for Ariana Grande confirmed the pop star was unhurt.

Train lines through the city’s Victoria station are currently blocked.

Police have yet to release information about the source of the blasts.