Investigators said it appears several fires broke out at the same time Friday in San Rafael, leading them to believe the 16-acre brush fire was deliberately set.
Investigators are interviewing witnesses and reviewing evidence of possible arson. Firefighters were still on the scene Saturday checking for hot spots.
The fire came dangerously close to about 100 homes, but no structures were lost, only minor damage to the exterior of three mobile homes, and no one was injured.
