The Riverside County Sheriff’s Department said they were working to identify the victim. The second person who died in the so-called Sandalwood Fire has been identified as 89-year-old Lois Arvikson. Her son Don Turner said she had called him to say she was evacuating, but he never heard from her again.

Some 100,000 residents were ordered out of their homes because of the wind-driven wildfire that broke out Thursday evening in the San Fernando Valley, though authorities began lifting evacuation orders in some areas Saturday. It spread westward through tinder-dry brush in hilly subdivisions on the outskirts of the nation’s second-largest city.

As of Saturday morning, fire officials said the Sandalwood blaze had burned 823 acres and was 25 percent contained. The Saddleridge Fire, in the city’s San Fernando Valley area, had burned 7,552 acres and was 19 percent contained.

One man who tried to fight the Saddleridge blaze died of a heart attack, and one firefighter reported a minor eye injury. The fire’s cause is under investigation, and authorities warned that the threat of flare-ups remained. Thousands of people remained under evacuation orders, though some were lifted Saturday.

Los Angeles Fire Department spokesman Brian Humphrey said the bulk of the fire at the city’s edge had moved away from homes and into rugged hillsides and canyons where firefighters were making steady progress slowing its advance. Television footage showed plumes of smoke rising from the area but no walls of towering flame, as a water-dropping helicopter moved in to dump another cascade on the blaze.

Firefighters worked under sunny skies, but air quality was poor as smoke dispersed over much of greater Los Angeles. Air quality officials urged people to limit outdoor activities.

The forecast called for low humidity — in the 10 percent range — with light wind and an occasional gust up to 15 mph.

Fire danger remained high for much of Southern California, with warnings in place for large swaths of Ventura and Santa Barbara counties west of Los Angeles.

The cause of the Los Angeles blaze wasn’t immediately known, though arson investigators said a witness reported seeing sparks or flames coming from a power line near where the fire is believed to have started, said Peter Sanders, a spokesman for the Los Angeles Fire Department.