Blainville intermunicipal police Insp. Francis Lanouette said they were called to the blaze at about 2 a.m.
He said the fire was at a home on Avalon Street.
About 45 firefighters came from Rosèmere, Boisbriand, Blainville and Sainte-Thérèse to put out the fire.
The surviving victim, a woman in her eighties, was taken to the hospital. Lanouette said the woman is in a stable, but critical, condition.
Police are investigating the cause of the fire.
According to Lanouette, the fire caused about $200,000 worth in damages.