Wildfires raging across southern California abated on Saturday with evacuation orders lifted after 100,000 people were forced to flee their homes.

A helicopter tries to put out the wildfire in California's Napa, the United States, on Oct. 10, 2017. The death toll has risen to 15 in north California wildfires as more casualties were confirmed Tuesday in several counties near San Francisco in western California in west United States. (Xinhua/Wu Xiaoling)

A fire that had burned rapidly through the San Fernando Valley in greater Los Angeles was the strongest of several across southern California.

By Saturday, it had consumed 3,200 hectares, about 32 kilometers north of downtown Los Angeles, fire officials said, adding that the blaze was about 33 percent contained.

All residents were allowed to return to their homes on Saturday as cooler temperatures and lighter winds improved the outlook.

"We are prepared for any flare-ups as they occur," Los Angeles fire captain Branden Silverman told local media.

One man in his 50s died of a heart attack as he struggled to save his home, fire officials said.

Part of Los Angeles County was blanketed with smoke from the fire, prompting an advisory from air quality officials about unhealthy conditions.

The fire broke out Thursday night and quickly grew out of control in the city of Sylmar, driven by low humidity and gusts known as the Santa Ana winds.

About 1,000 firefighters, backed by water-dropping helicopters and planes releasing fire retardants, fought the blaze that forced the shutdown of several major highways.

The metro line in the area was also closed as were schools and businesses.

Some 200 firefighters battled several other blazes in Riverside County, east of Los Angeles, including one that tore through a trailer park and was started by burning trash.