Fire officials say three fires in west-side neighbourhoods during a 24-hour period are considered suspicious in origin.

The most serious was a fire early Monday at an unoccupied house in the 300 block of Avenue J South that saw fire crews arrive to find the rear of the house fully involved in flames.

Firefighters extinguished the flames but a thermal imaging camera revealed the fire had spread to the walls and attic of the structure, forcing crews to continue the attack. Their work was complicated by several types of insulation present in the structure, Saskatoon Fire and Protective Services said in a news release.

Two suspicious fires early Sunday included a vehicle fire at 30th Street West and Avenue I North and a garage fire on Avenue K South near 10th Street West. Damage was estimated at less than $5,000 in the garage fire.

Meanwhile Sunday, a fire caused by cooking on the main floor of a house on the 1300 block of Osler Street resulted in $40,000 in damage.

Fire crews from three stations arrived just after 8:30 p.m. to find heavy smoke showing from the front of the home and light smoke from the rear and side of the home.

Tenants from the main floor and basement suite left the house before firefighters arrived at the scene and no one was injured,