The incident happened at about 8:30 p.m. in a triplex on Hôtel de Ville Avenue, between Mont-Royal Avenue and Marie-Anne Street.
Last night, witnesses said a gas barbecue exploded, but police are not confirming those reports this morning.
As they arrived on the scene, firefighters said they could smell propane.
Montreal police Const. Simon Delorme said investigators are still trying to determine the cause of the explosion.
“The investigation is transferred to Montreal Police department — the arson unit — which is going to try to explain what happened exactly, because it is really fuzzy situation right now,” Delorme said.
The victim was found with severe burns and was rushed to the hospital.
Police say the burns are making it difficult to identify the man.