The fire sparked just after 6:30 p.m. in the near triple-digit temperatures and bone-dry brush.
The blaze scorched at least 35 acres as of Sunday night, and officials say it has the potential to grow. It is zero percent contained.
No evacuations have been ordered, and Highway 2 is shut down from Highway 138 to the Sheep Creek area, according to the San Bernardino County Fire Department.
An Angeles National Forest fire service spokesperson said the brush fire was burning close to homes on Desert Front Road, but it was unclear if those homes were in any immediate danger as water-dropping helicopters continue their aerial attack on the blaze.
The cause of the fire is under investigation.
This is a developing news story. Updated information will be posted here as it becomes available.