According to Cal Fire, the fire is burning near Deer Creek Road in Boulder Creek.
The Santa Cruz Co. Sheriff's Office says they are not evacuating the area at this time. There is heavy brush where the fire is burning and few homes.
Bear Creek Rd. is closed from at 17 to allow emergency vehicle access.
No traffic is allowed beyond mile marker 6.89 on Bear Creek Rd. leaving Boulder Creek. The road is also closed at Bear Creek Rd. and Bear Creek Canyon.
Officials say that more than 150 firefighters will remain on the line overnight, building and reinforcing containment lines.
One firefighter had a mild injury, Cal Fire says.
Brush fire burning in Santa Cruz Mountains