The Apple Fire was 30 percent contained Thursday morning, having scorched 28,085 acres.
The fire remains in the San Gorgonio Wilderness.
On Thursday, firefighters focused on the Oak Glen area in Millard Canyon.
The fire remained on the west side of Millard Canyon; and in the Oak Glen area, the fire is slowing.
Firefighters in Cherry Valley and Banning Canyon are cleaning up and leaving, due to inactivity.
Firefighters continued to build a containment line in Millard Canyon with air tanker support with fire retardant on Thursday.
On Wednesday, the blaze was spreading northeast into the San Gorgonio Wilderness. Investigators say the Apple Fire started last Friday from hot debris out of a vehicle’s faulty exhaust system that shot into brush.
As of Wednesday, firefighters have built lines to protect Oak Glen and Forest Falls on the west side.
The control line that firefighters worked on to control the fire’s spread was in the area of Pine Bench.
Hand crews and bulldozers were working along Yucaipa Ridge to build a fire break, authorities said.
The control line was considered critical in the protection of Oak Glen and Forest Falls. Riverside County has ended mandatory evacuations east of Oak Glen Road, west of Potrero Road and north of Wilson Street.
However, San Bernardino County continued its Oak Glen evacuation order east of Oak Glen Road, including Potato Canyon and Pine Bench north of the Riverside-San Bernardino County line. Evacuation warnings remained in effect on Wednesday east of Potrero Road, north of Morongo Road, and west of Whitewater Canyon.
The Beaumont High School evacuation center was closed Tuesday night.
Four homes and eight other structures have burned, one firefighter has been injured, and Cal Fire estimated 2,586 homes had been forced to evacuate, affecting 7,800 people.