Two people are dead after fire broke out and heavy smoke filled a rooming house in Montreal's Pointe-Saint-Charles neighbourhood overnight.

The 51-year-old man and 80-year-old woman were unconscious when they were pulled from the Favard Street building by firefighters just before 11 p.m. Sunday.

Const. Raphael Bergeron of the Montreal Police said they were pronounced dead in hospital.

A third person was taken to hospital to be treated for smoke inhalation, but the injuries are not considered life threatening.

The investigation has been turned over to the Montreal police because of the fatalities.

Officials are still investigating the cause, but they believe the fire may have started in the kitchen.

Initially, fire officials said there were no working smoke detectors in the building.

Later in the day, operations Chief Benoit Brouillard said in fact three out of the four detectors in the house were functional, but the residents didn't hear them.