Police patrolling the Hochelaga-Maisonneuve neighbourhood noticed flames around midnight coming out of an apartment building at the corner of Joliette Street and Ontario Street East.
At least 100 firefighters worked to put out the flames early Thursday morning. Crews rescued two people from windows on the upper floors of the building, according to Montreal Const. Danny Richer.
Once the fire was under control, firefighters discovered two bodies inside.The deaths were the 27th and 28th homicides of the year.
Officers said the fire was criminal.
Arson squad investigators found traces of an accelerant between the second and third floors of the building, according to CBC reporter Elias Abboud.
A man in his fifties suffered burns to his upper body and a 34-year-old woman is being treated for smoke inhalation. Both were sent to the hospital.
The Montreal police arson squad is overseeing the investigation.