By Amy B Wang, (c) 2017, The Washington Post

A fast-spreading brush fire north of Los Angeles forced hundreds of people to evacuate their homes Friday and Saturday as firefighters struggled against triple-digit temperatures and erratic winds to contain the blaze, officials said.

Within a day, the wildfire – named the La Tuna Fire for its origin in La Tuna Canyon to the north of Burbank – had grown to cover more than 5,000 acres, according to the Los Angeles Fire Department. In all, about 300 homes in Burbank, 250 homes in Glendale and 180 homes in Los Angeles were under evacuation as of Saturday afternoon.

As of Saturday, the fire was 10 percent contained. Although no injuries were reported, one home had been destroyed, the fire department said.

“This continues to be a very dynamic fire,” Los Angeles Fire Chief Ralph M. Terrazas said at a news conference Saturday. “The weather conditions are somewhat stable, but that could change at any moment.”

Terrazas added he was confident the fire had burned “well above” 5,000 acres as of Saturday afternoon, but he was not able to give a fixed acreage. Earlier in the day, Los Angeles Mayor Eric Garcetti confirmed that by acreage, the blaze was the largest in the city’s history.

Fire officials said erratic wind and weather were posing the greatest challenges to extinguishing the fire. Authorities were particularly concerned about how quickly the blaze could spread in the area’s canyons.

“This is a slow burning, ‘backing’ fire (meaning it burns down hill) and we have resources at the base of the hills to defend homes,” fire spokeswoman Margaret Stewart said in a statement. “When the fire encounters a canyon, it can accelerate and burn uphill.”

Video taken Saturday morning near La Tuna Canyon Road, over the hills to the north of Burbank, showed flames and heavy smoke.

The La Tuna Fire was first reported about 1:30 p.m. Friday as a small, one-acre vegetation fire south of Interstate 210 near Burbank. Although firefighters quickly extinguished the bulk of that fire, high winds caused embers to jump across the highway, sparking a spot fire north of I-210, Stewart said.

Within a few hours, more than 250 firefighters from multiple agencies had been dispatched to the fire, which had grown to 500 acres and shut down a portion of I-210.

By 9 p.m. Friday, the fire had tripled in size to 1,500 acres. Authorities soon ordered mandatory evacuations, street by street, for neighborhoods in Burbank closest to Verdugo Mountain Park. A surreal scene unfolded in Burbank as bright flames could be seen coming over the hilltops to the north of the city.

Nearly 200 homes in Burbank were evacuated late Friday, with police officers going door to door throughout the night to ensure residents had left the area. Police continued to enforce new mandatory evacuation orders throughout Saturday.

Just before midnight, the Los Angeles Fire Department reported that the La Tuna Fire was burning in four directions, including down over the hills toward Burbank and north through the La Tuna Canyon above I-210. The fire’s “erratic” spread was “driven by strong, gusting winds,” the agency said.

California has been experiencing a severe heat wave, expected to last through Labor Day.

Carol Smith, a National Weather Service meteorologist, told the Los Angeles Times that a combination of conditions were working against firefighters: temperatures of up to 106 degrees, 50-mph gusts of wind and unstable air.

“It just really stokes the fire,” Smith told the newspaper. “I mean, when it’s hot and the gusty winds, it’s been a bad mix of different things.”

As of Saturday afternoon, more than 500 firefighters were on scene, and a large portion of I-210 remained closed. Officials cautionedresidents in the area to stay indoors and avoid outdoor activities because of heavy smoke. Police expect mandatory evacuation orders to remain in place into Sunday afternoon.

“Despite fire size, we remain confident in the plan in place and the work all firefighters at the incident are doing in defending property and lives,” the Los Angeles Fire Department said.