The fire is burning near Kirker Pass Road and Nortonville Road near Clayton and Pittsburg.
CAL FIRE said the blaze started from a car fire and had a "moderate rate" of spread, but forward progress has been stopped.
Kirker Pass Road is closed from Hess Road in Concord to Buchanan Road in Pittsburg, the fire department said.
CAL FIRE said crews will remain at the scene for two to three hours.
This is developing, check back for updates