Inappropriately stored staining rags may be the cause of a fire that badly damaged an east Santa Rosa home early Tuesday, according to a Santa Rosa fire official.

The 3 a.m. blaze burned about one‑third of the Carissa Avenue, split‑level home, with damage estimated at $300,000, Battalion Chief Matt Dahl said.

Two adults and three children got out safely after the father smelled smoke and rounded everyone up and over to a neighbor’s home.

Arriving Santa Rosa firefighters found flames in the garage, first and second floors. “We used heavy streams to knock it down from the exterior then switched to an interior attack,” Dahl said.

A total of 32 firefighters, seven engines and one ladder truck fought the fire, from Santa Rosa, Rincon Valley, Bennett Valley and Cal Fire. Red Cross volunteers also arrived to help the family.

The fire was under control in about 30 minutes. Much of the split‑level home was saved, but smoke damaged unburned portions, Dahl said.

A preliminary cause may be spontaneous combustion from the staining oils and possible solvents on a drop cloth stored in the garage, Santa Rosa Assistant Fire Marshal Ian Hardage said. But investigators still were eliminating other possibilities.

Carissa Avenue is in Bennett Valley, off Summerfield Road.

You can reach Staff Writer Randi Rossmann at 707‑521-5412 or randi.rossmann@pressdemocrat.com. On Twitter@rossmannreport.