Firefighters in a mountainous area north of Los Angeles made good progress in their battle against a brush fire that has forced thousands of people to evacuate, officials said on Friday (local time).

The Canyon Fire ignited on Thursday afternoon and spread rapidly in the dry, steep terrain in Ventura and Los Angeles counties to more than 22 square kilometers.

It was 25 per cent contained as of Friday afternoon, according to the Ventura County Fire Department.

At least 400 personnel battled the blaze along with several planes and helicopters, county fire department public information officer Andrew Dowd said.

The fire is burning just south of Lake Piru, a reservoir located in the Los Padres National Forest. It’s close to Lake Castaic, a popular recreation area burned by the Hughes Fire in January.

That fire burned about 39 square kilometers in six hours and put 50,000 people under evacuation orders or warnings.

Firefighters battling the Canyon Fire took advantage of lower temperatures overnight to directly attack the fire and made lots of progress, Dowd said.

By Friday morning, they were seeing subdued fire behavior, he said.

With 100-degree temperatures and strong winds, firefighters faced a “tough firefight” on Thursday, Dowd said.

“They were putting it all on the line to bring this fire under control,” he said.

One firefighter reported a minor injury, but no civilian injuries were reported, Dowd said.

No single-family or multi-family residences were destroyed, but two minor structures were destroyed, he said.

Sunny, hot and dry conditions were expected on Friday in the area where the Canyon Fire was burning, with the daytime high near 38 degrees Celsius and minimum humidity in the mid-teens, according to the National Weather Service.

Winds were expected to be light in the morning and grow from the south to southwest in the afternoon.

The wind was expected to stick around onFriday, but at a slightly lower magnitude, according to Bryan Lewis, a meteorologist at the weather service’s office in Oxnard.

The humidity was expected to remain low, and the fuels were very dry and receptive to burning quickly, he said.

Given these conditions, people should be very careful to avoid sparks, he said.

“These fires can start and grow pretty rapidly because of how dry everything is and how hot everything is,” he said.

In LA County, around 2,700 residents evacuated with 700 structures under an evacuation order, officials said late on nThursday.

Another 14,000 residents and 5,000 structures were covered by an evacuation warning. Areas within the Val Verde zone had been reduced from an order to a warning.

The evacuation zones in nearby Ventura County were relatively unpopulated, Dowd said. Fifty-six people were evacuated from the Lake Piru recreation area.

LA County Supervisor Kathryn Barger, who represents the district, urged residents to evacuate.

“Extreme heat and low humidity in our north county have created dangerous conditions where flames can spread with alarming speed,” Barger said in a statement.

“If first responders tell you to leave, go — without hesitation.”

The new blaze comes as a massive wildfire in Central California became the state’s largest blaze of the year, threatening hundreds of homes and burning out of control in the Los Padres National Forest.

The Gifford Fire had spread to 402 square kilometers by Friday morning with 15 per cent containment.

It grew out of at least four smaller fires that erupted August 1 along State Route 166, forcing closures in both directions east of Santa Maria, a city of about 110,000.

It has injured at least four people. The causes of the fires are under investigation.

Wildfire risk will be elevated through the weekend across much of inland California as a heat wave gripping the area intensifies.

August and September are typically the most dangerous months for wildfires in the state.