One person is dead and another injured after a gunman opened fire behind Parti Quebecois headquarters in Montreal as PQ Leader Pauline Marois delivered her election victory speech Tuesday night.

The incident at the Metropolis concert hall prompted Marois’s security detail to whisk her off stage and evacuate the building.

Montreal police arrested a 50-year-old man at the scene, clad in what appeared to be a long, blue housecoat and a makeshift balaclava.

Police said they believe the suspect also lit a small fire near PQ headquarters after the shooting, before he tried to flee.

The man was handcuffed and placed in a police cruiser in front of cameras and a crowd that had assembled outside. The Canadian Press reports that the suspect shouted in French: "The English are waking up!"

Police did not immediately release any details about the shooting victims, nor would they comment on the suspected shooter’s possible motive.