Thunder Bay firefighters tackle a blaze at a Riverdale home on Thursday. (Gary Rinne/CBC)

Thunder Bay Fire Rescue says a fire that substantially damaged a home on Riverside Drive was caused by the careless disposal of smoking material.

The city's captain of fire prevention said Thursday's fire started in an attached garage and spread quickly once it reached the home's attic.

Eric Nordlund said it's a good reminder to be very careful disposing cigarettes. "With the weather being as cold as it is, people aren't smoking outside as much," he said.

"In this case, someone was smoking in the garage and that's what lead to this fire." The safest way to dispose of smoking materials is in a metal container, not a garbage receptacle, according to the fire service — and the container should always be kept outside.

Nordlund said at least two people lived in the home and are temporarily staying with with friends and family.