LONDON (AP) — British police are investigating an acid attack at a London club that led to a mass evacuation.

Police said Monday 12 people were treated in hospitals for burns. None of the injuries was said to be life-threatening. Two men in their 20s were in serious but stable condition.

Police say the problem at the Mangle nightclub in east London started with a dispute between two groups of people that escalated when a male suspect sprayed a "noxious substance" directly at two men.

Roads in the area were closed and a hazardous material response team rushed to the scene.

The substance hasn't yet been identified.