The fire occurred at 901 Bailey Road near the border of Bay Point, just south of a landfill in the area, the Contra Costa Fire Protection District said on social media early Friday.
Crews have contained the blaze with no structures affected, according to fire officials, who added that the fire is wind-driven.
They say the fire started due to a vehicle fire just before 2 a.m. and grew into vegetation, burning 50 acres.
The portion of Bailey Rd between Bay Point and Concord is shut down in both directions. Motorists are advised to avoid the area.