LOS ANGELES — A wind-driven brush fire carved a devastating path in the northern foothills of the San Fernando Valley on Friday, chewing through 7,500 acres, burning at least 25 homes and forcing thousands to flee.

The Saddleridge fire, which broke out about 9 p.m. Thursday on the north side of the 210 Freeway in Sylmar amid strong Santa Ana winds, spread rapidly westward into Porter Ranch and other communities. At its peak, the blaze was moving at a rate of roughly 800 acres per hour.

It was 13% contained as of Friday afternoon, Los Angeles fire officials said.

Mandatory evacuations were issued overnight to roughly 23,000 homes encompassing a large swath of neighborhoods north of the 118 Freeway from Tampa Avenue all the way to the Ventura County line — an area covering 100,000 residents. Officials warned that other communities near the fire need to be ready to leave at a moment’s notice if the winds shift.

“The fact that community members heeded evacuation warnings early made a huge difference, allowing firefighters to enter those communities and protect properties,” said Los Angeles County Fire Chief Deputy David R. Richardson.

Conversely, Los Angeles Police Department Chief Michel Moore said he’s seen homeowners stay behind to battle raging flames on their property with garden hoses. He urged residents to evacuate when ordered.

“Those individuals placed not only themselves in imminent peril, but they placed first responders such as police and fire officials in that same perilous condition because of our need and desire to go in and try to rescue them,” Moore said.

One firefighter suffered a minor injury to his eye while battling the blaze, and a man in his late 50s died after suffering a heart attack while talking with firefighters early Friday, officials said. Authorities could not confirm reports that the man was trying to fight the fire from his home before he was stricken.

More than 1,000 firefighters from multiple agencies continued attacking the blaze from the air and ground and by Friday afternoon conditions appeared to be improving, officials said.

Helicopters and amphibious firefighting aircraft known as Super Scoopers were deployed, while ground crews manned bulldozers to cut containment lines into nearby hillsides in an effort to slow the fire’s spread. At least one air tanker blanketed fire retardant across the ridges between Granada Hills and Porter Ranch.

However, low humidity and northeasterly winds gusting up to 50 mph, which are expected to linger until the evening, still pose a challenge for firefighters. Officials say they expect it will take days to get the blaze completely under control.

Hannah Fry, Marisa Gerber, Leila Miller, Matthew Ormseth, Joseph Serna and Matt Stiles are Los Angeles Times writers.