Emergency crews are at the scene of an explosion in Montreal's Rosemont borough that left 5 people injured

Firefighters are working to determine whether a building in Montreal's Rosemont borough is structurally sound after an explosion and fire tore through the building Sunday afternoon, leaving five people injured.

The explosion occurred at around noon at a three-storey, 52-unit rooming house at 1460 Bélanger Street, between Garnier and Fabre streets, on the border of Montreal's Rosemont—La-Petite-Patrie and Villeray boroughs.

The force of the explosion blew out the building's windows.

Five people were injured in the blast, three of whom were taken to hospital.

Bob Lamle of Montreal's Urgences-Santé said two of those taken to hospital were men with first- and second-degree burns to 60 to 70 per cent of their bodies. He said the third victim suffered minor injuries.

One firefighter suffered minor injuries but was not taken to hospital.

Firefighters were able to extinguish the fire shortly after the explosion.

"Fire is now satisfied, they've done two sweeps of the building and they are confident that there is no one else left in the building," Lamle told CBC News.

Montreal police spokeswoman Const. Lynn Duncan said officers evacuated several nearby buildings and are controlling the crowd.

The cause of the four-alarm incident has not been determined. Fire officials believe the explosion might have happened in a corridor near the building's stairwell.