A California brush fire that broke out and quickly grew during the first day of an extreme heat wave, closing a major highway, was burning more than 5,000 acres.
The Route Fire, burning near Castaic, north of Los Angeles, spanned 5,200 acres on Friday. Interstate 5 was closed in both directions Wednesday night due to the blaze.
The inferno is 37% contained and so far two structures have been destroyed. Officials said some 550 structures were threatened by the flames.
The cause of the fire is not yet known, and is under investigation.
The fire broke out west of Interstate 5 around noon Wednesday, Los Angeles County Fire Capt. Sheila Kelliher-Berkoh said, and it occurred as most of California was under an excessive heat warning.
Temperatures of 109 degrees were recorded in the area shortly before 2 p.m. Wednesday, according to the National Weather Service.
“We’re really at day one of about a nine to 10 day fairly extreme heat period,” Los Angeles County Deputy Fire Chief Tom Ewald said at a news conference.
“If you can imagine wearing heavy firefighting gear, carrying packs, dragging hose, swinging tools — the folks out there are just taking a beating,” he said.
Fire officials said Thursday that excessive heat, low humidity and steep terrain will “continue to pose the biggest challenge for firefighters today," together creating a dangerous combination with potential for “large plume growth, uphill runs and short range spotting.”
Eight firefighters suffered heat-related injuries, and six were taken to hospitals, Ewald said Wednesday. As of Thursday all of them have been released from the hospital and are doing well, NBC Los Angeles reported.
Evacuations have been ordered in Paradise Ranch Mobile Estates, south of Templin Highway, north of Lake Hughes Road, east of the Golden Station Freeway, west of Castaic Lagoon and north of Northlake Elementary school.
Two Red Cross shelters have been set up at West Ranch and Frazier Mountain high schools.
More than 350 firefighters from Los Angeles County and the U.S. Forest Service, as well as 15 aircraft, were fighting the fire Wednesday, Kelliher-Berkoh said. Between 100 and 200 homes were evacuated, Los Angeles County Sheriff’s Lt. Brandon Barclay said Wednesday.
Interstate 5, a major route between Los Angeles and northern communities like Bakersfield, has slowly reopened since Wednesday.
The highway between Lake Hughes Road and Templin Highway reopened one northbound lane and two southbound lanes, California’s Department of Transportation said early Thursday.
More than 35 million people were under excessive heat warnings Wednesday across the West and the Southwest and in most of California, as well as parts of Nevada and Arizona, according to the weather service.
Another blaze in Southern California, the Border 32 Fire, prompted the closure of the Tecate border crossing, U.S. Customs and Border Protection said.
The fire in San Diego County, which began shortly after 2 p.m. Wednesday, had burned nearly 4,500 acres and was 20% contained by Friday, fire officials said.
The blaze has destroyed 10 structures.
The potentially record-breaking heat wave in Southern California is forecast to continue into next week, according to the weather service.
CORRECTION (Sept. 1, 2022, 7:45 a.m. ET). A previous version of this article misstated where the Route Fire started. It broke out west of Interstate 5, not east.