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The Sun via AP, Micah Escamilla
Local residents display signs for firefighters as the Lake Fire continues to burn Sunday, June 21, 2015, in Angelus Oaks, Calif. Firefighters working amid sweltering conditions in steep terrain were aided by a fleet of water-dropping aircraft in attacking flames in the mountainous wilderness about 90 miles east of Los Angeles.

LOS ANGELES — Cooler weather Monday was expected to aid crews making progress against a huge forest fire in a remote area of the San Bernardino Mountains — the largest of several blazes burning across California.

The fire about 90 miles east of Los Angeles was 21 percent contained and holding steady at about 27 square miles as firefighters attacked the flames with a fleet of water-dropping aircraft.

About 500 buildings, including old cabins, had been threatened, but none were lost. The flames forced several hundred people to leave camps and vacation homes in the mountains.

The National Weather Service said a high pressure system that pushed temperatures into triple digits in Southern California over the weekend was drifting east, prompting gradual cooling and increasing humidity.

The cause of the fire that began Wednesday remained unknown.

In Northern California, reinforcements were on the way to help battle a wildfire south of Lake Tahoe where the tiny town of Markleeville was on standby for possible evacuations.

The blaze was about 10 percent contained after burning nearly 14 square miles of timber and grass since it broke out Friday and forced the evacuation of some campgrounds, said Sierra Front fire spokeswoman Jenny Ramella.

Elsewhere, a blaze that burned at least two homes near Santa Margarita in Central California held steady at just under 3 square miles. Helicopters took water from nearby Santa Margarita Lake to dump on the blaze that was 60 percent contained.

Glenn Westbrook said he and his son grabbed the family's goat, rooster and dog as the flames closed in on Sunday. When they returned, their home was a smoldering pile of rubble.

"It was pretty much ashes. It was pretty much gone," Westbrook told the San Luis Obispo Tribune.

A 920-acre fire in Madera County destroyed three structures and led to the evacuation of a handful of homes. It was 75 percent contained.

Firefighters also made gains against a blaze in Sierra National Forest, south of Yosemite National Park, that burned 500 acres of dry brush.

The fire was 40 percent contained after prompting the closure of some camp sites.

Three air tankers doused the blaze that officials believe was started by a vehicle.

Associated Press writers Scott Sonner in Reno and Kristin Bender in San Francisco contributed to this story.