The fire is burning in the Samuel P. Taylor State Park in an area difficult for firefighters to access. It was first reported around 8 p.m. At least 20 to 30 structures are being threatened and the fire was 10 percent contained as of midnight.
Evacuated residents were advised to go to the Lagunitas School and await further instructions.
Smoke in the San Geronimo and Fairfax communities could be strong due to the fire.
Find the latest evacuation information from the Marin County Fire Department.
Some road closures are also in effect, and a public information hotline has been set up for residents to call.