The fire, dubbed the Charlie Fire, was reported shortly before 3 p.m. in the 31000 block of Charlie Canyon Road.
The blaze started around 3 acres and then quickly grew to 100, fire officials said. The blaze eventually grew to about 3,000 acres and reached 10 percent containment.
Fire crews said helicopters and additional aircraft were requested for water drops.
Evacuation orders were issued for San Francisquito Canyon Road, with 20-50 homes affected near Camp 14. The road is closed from camp 14 to Lowridge Place.
#LASD Assisting our @LACOFD in redirecting traffic on Lake Hughes Rd. 20-50 home evacuated near Camp 14 on San Francisquito Cyn. No structures threatened or damaged at this time. pic.twitter.com/ewiCqFpNl2— LA County Sheriff's (@LASDHQ) September 23, 2018
An evacuation center was set up at Castaic Sports Complex, 31210 Castaic Road.
Lake Hughes Road from Ridge Route to Dry Gulch was closed.
Temperatures in the area hit 96 degrees amid 21 percent humidity and light winds, but fire officials noted wind gusts reached up to 19 mph.
The cause of the fire remains under investigation.