A man in his forties is missing following a fire at a triplex in the Villeray-St.Michel borough.

At 10:15 Monday morning, an explosion and fire forced more than a dozen residents from their homes on Christophe-Colomb Ave. near Villeray St.

The five-alarm fire quickly spread to the upper floors and roof of the triplex.

A team of 150 firefighters worked to battle the blaze, as traffic was closed on Christophe-Colomb

Less than two hours after the fire began, the roof of the building collapsed.

Authorities say the fire was caused by some type of explosion in an apartment on the third storey orf the triplex, but could not determine what caused it.

Daniel Berchou was visiting friends next door to where the explosion took place and described the explosion as extremely loud.

“In our place, the wall was pushed 20 centimetres and the windows were blown out,” he said.

A 43-year-old living inside the home suffered minor injuries to his knee. His roommate is now missing and firefighters believe he may be trapped inside.

Police have so far been unable to locate him due to damage and debris caused by the roof collapse.

The building was deemed structurally unsound Monday afternoon and was carefully taken down, in the event a body may be found inside.

Four people who were living there are now homeless.

“The explosion made the structure very unsafe. It’s unsafe for our firefighters to go inside to verify the structure and it’s safer for the people living on either side also, for us to take the building down,” said Ian Ritchie, chief of operations for the fire department.

The Montreal police arson squad is also investigating what caused the fire and isn’t ruling out that it might have been criminally set.

Meanwhile nine people were evacuated from the two adjoining buildings and they do not yet know if or when they will be allowed to return home.

“They are going to have to check the foundation just to see that everything is okay, but not tonight… We'll know more tomorrow,” said Borough Mayor Anie Samson.

They can’t return until they are declared safe.