MONTREAL (Reuters) - A gunman shot and badly injured two people inside the Montreal theater where separatist leader Pauline Marois was giving a speech in the wake of a narrow election win, police said early on Wednesday.

Bodyguards rushed Marois from the stage in the wake of the shooting. She later returned to the podium to finish her speech.

Police spokesman Danny Richer said a man of around 50 had been arrested. The suspect also set fire to the back of the building, he told reporters.

The incident is highly unusual for Canada, where rates of gun crime are relatively low and many politicians move around without bodyguards.

RDI television showed pictures of police subduing a large man with a rifle who was dressed in a black cape.

He appeared to shout in French the phrase "The English are waking up." Marois heads the separatist Parti Quebecois, which wants independence for the French-speaking province of Quebec.

She is also promising to strengthen laws designed to ensure the dominance of the French language, which has worried some in the minority English-speaking community.

Parti Quebecois won a minority government in a provincial election held on Tuesday, returning to power after nine years in the opposition.

(Reporting by Rita Devlin Marier, writing by David Ljunggren; editing by Todd Eastham)