MONTREAL -- A Laval home was heavily damaged by fire Friday morning.

The fire started just before 8 a.m. in an unoccupied single-family home on Lévesque Boulevard East in the Duvernay sector. 

"Our teams are on the defensive because the structure is not safe," the firefighters stated on Twitter. "The roof has collapsed."

Investigators are trying to determine the cause. Firefighters said smoke and flames could be seen coming from the basement.