UPDATE 7 p.m.: The fire has been contained at 35 acres, according to Cal Fire.
UPDATE 5:30 p.m.: About 35 acres have been burned by the wildland fire northeast of Cayucos, according to a tweet from San Luis Obispo County Cal Fire. Containment of the fire was expected by 5:45 p.m.
Original story: Firefighters are on the scene of a four-acre brush fire northeast of Cayucos.
The fire, at the end of Thunder Canyon Road, was spotted by a CHP aircraft. No homes are threatened.
A Cal Fire spokesman said the fire is spreading at a slow rate of speed and that firefighters are making progress containing it. Crews from Cayucos, Morro Bay and Cambria are assisting.