The blaze has burned about 46 square miles in mountain and canyons areas, destroying at least six houses and damaging 15 more.
The fire was fueled in part by chaparral that was "extremely old and dry" and hadn't burned since 1929, U.S. Forest Service Incident Commander Norm Walker said Sunday at a news conference.
More than 2,800 people and 700 homes were under evacuation orders that were expected to last until late Monday or Tuesday.
About 2,100 firefighters took on the flames, aided by water-dropping aircraft, including three helicopters that stayed aloft through the night.
"We're putting everything that we have into this," Walker said.
The cause of the fire was under investigation. Three firefighters had minor injuries, but no one else was hurt.
Winds of about 25 mph and gusting as high as 40 mph had created "havoc" for firefighters for much of Sunday, LA County Deputy Chief David Richardson said.
Propelled by the strong winds, the fire jumped an aqueduct west of Lancaster, officials said.
George Ladd, 61, said among the structures burned was a cabin at Lake Hughes his family had owned since 1954 but sold just last week. He said he expected it may go up in flames sooner.
"We had always worried about that thing going off like a bomb," Ladd said.
He walked through the ashes of his former cabin and the other destroyed homes Sunday.
"All of them are nothing," Ladd said by phone from his home in nearby Palmdale later Sunday night. "A few scraps, a few pieces of wood with nails sticking out, but mostly just broken up concrete."
Also in the West, two major wildfires are burning in northern New Mexico, and weather conditions were not expected to be helpful to firefighters Monday.
The Tres Lagunas fire north of Pecos in the Santa Fe National Forest had grown to 12 1/2 square miles by Monday morning, causing smoke to spread across much of the region. It earlier prompted the evacuations of about 140 houses, most of them summer residences.
Drier and windier weather was expected Monday, a change from Sunday, said interagency fire management team spokeswoman Denise Ottaviano. "It's going to be challenging."
The Thompson Ridge fire near Jemez Springs remained at nearly 3 square miles, according to a Monday morning status report. Forty to 50 houses were evacuated late last week.