(Reuters) - More than 1,000 firefighters battled a deadly and fast-moving wildfire on the northern edge of Los Angeles on Saturday, reinforcing containment lines that allowed thousands of residents under evacuation orders to return to their homes.

The wind-driven blaze, dubbed the Saddleridge fire, broke out on Thursday night and raced through the area’s dry foothills and brush-filled canyons to cover some 7,552 acres (3,056 hectares) by midday on Saturday.

The Los Angeles Fire Department said the fire was 19 percent contained after “aggressive” overnight air operations in support of ground crews, up from 13 percent a day earlier.

All mandatory evacuation orders were lifted over the course of the day, Mayor Eric Garcetti said.

“My heart goes out to those who have been impacted,” Garcetti said in a statement. “I am deeply grateful to the firefighters and first responders ... These brave women and men saved lives — and if not for their quick action, we know the destruction would have been much worse.”

At least one death has been attributed to the Saddleridge fire, a man who authorities said suffered a heart attack while trying to fight encroaching flames on his property rather than heeding evacuation orders.

Two firefighters suffered minor injuries, the LAFD said, and 31 structures have been either damaged or destroyed.

The cause of the blaze was under investigation.

The Saddleridge is the largest among a spate of wildfires across Southern California.

On Saturday, authorities said the 820-acre Sandalwood Fire in Riverside County, about 70 miles (110 km) east of the Saddleridge fire, was 25% contained, up from 10% on Friday.

The Sandalwood Fire has killed at least two people: one was an 89-year-old woman and the other has not yet been identified, according to Riverside Deputy Sheriff Robyn Flores.

They were found in separate mobile homes on Thursday and Friday at the Villa Calimesa Mobile Home Park, Flores said.