The wildfire burning near Lake Hughes was 38% contained Monday evening, but it grew to 19,026 acres amid temperatures reaching 103 degrees earlier in the day.
Containment of the Lake Fire increased from 31% Monday morning and 12% Sunday, according to the Los Angeles County Fire Department. Full containment is not expected until Sept. 2.
One person suffered an injury, but further details were not immediately available.
The flames have destroyed 12 structures and 21 outbuildings and damaged three other structures. An estimated 4,570 structures remain threatened, fire officials said.
Fire commanders reported Monday that 1,894 firefighters were battling the blaze, along with 12 helicopters, 23 water tenders and 189 engines.
Evacuations remained in effect for the following areas: Lake Hughes Road west of Pine Canyon and north of Dry Gulch Road, east of Ridge Route Road, west of Lake Hughes Road and Fire Station 78, north of Pine Canyon and Lake Hughes Road, and south of state Route 138.
The evacuation site at Highland High School in Palmdale was closed about noon on Monday, according to the American Red Cross. The Castaic Sports Complex evacuation center was closed Friday.
The Red Cross said it would set up an additional evacuation center at the Antelope Valley Fairgrounds in Lancaster, if needed, and would also provide virtual assistance to affected residents.
Animal boarding was available at the Castaic Animal Care Center. Large animals were being taken to the Antelope Valley Fairgrounds.
San Francisquito Canyon Road was reopened Monday, but road closures remained in place on Three Points Road from state Route 138 to Pine Canyon, Old Ridge Route from Highway 138 to Pine Canyon, and Lake Hughes Road from Ridge Route Road to Pine Canyon.
Poor air quality in and around the area of the fire was expected to affect the public and first responders.
The fire was first reported about 3:30 p.m. Wednesday near North Lake Hughes Road and Pine Canyon Road in the Angeles National Forest, according to the U. S. Forest Service, which was battling the blaze with Los Angeles County Fire Department crews and assistance from the Los Angeles, Culver City, Beverly Hills, Monterey Park, Long Beach and Santa Monica fire departments.
“There have been areas of this fire that have not burned in decades, (and) it’s in inaccessible terrain, which has added to the complexity of the fire,” said Los Angeles County Fire Department Chief Daryl Osby.
Although some structures were lost, a number of structures were saved by firefighters, he said.
The cause of the fire remains under investigation.