"There is a potential threat to life and/or property," the Sheriff's Department said. "Those who require additional time to evacuate, and those with pets and livestock should leave now."
Highway 62 was suggested as an evacuation route in either direction.
The Apple Fire has charred 28,085 acres and destroyed four homes since Friday.
A firefighter was injured Thursday when a tree fell, striking his head. He was treated and the injury was considered minor.
Fire officials estimate the blaze could be fully contained as soon as Aug. 17, according to Kate Kramer of the U.S. Forest Service.
Officials estimated that 2,600 residences and 7,800 people have been evacuated since the blaze erupted in Cherry Valley about 5 p.m. Friday in the area of Apple Tree Lane and Oak Glen Road.
#AppleFire Morning Update August 6, 2020— San Bernardino National Forest (@SanBernardinoNF) August 6, 2020
Size: 28,085 acres
Percent contained: 30%
Strategy: Full Suppression
Total Personnel: 2,591
Up-to-date incident information can be found at https://t.co/FV8GOXQy4l pic.twitter.com/M4h3x0ImpS