Video has surfaced showing the frantic scenes as the worst gun rampage in American history unfolded at a gay nightclub in Orlando, Florida on Sunday.

The footage – apparently taken by a club-goer who managed to escape – shows emergency services flocking to the scene.

In the video, the distinct sound of rapid gunfire can be heard in the background, as terrorist Omar Mateen opened fire on innocent civilians. Police shot him dead after a standoff, and said he had been carrying an assault rifle and a pistol.