Herman Termeer, 54, stands on the roof of his home as the Blue Ridge Fire burns along the hillside, Oct 27, 2020, in Chino Hills, California. Facing extreme wildfire conditions this week that included hurricane-level winds, the main utility in Northern California cut power to nearly 1 million people while its counterpart in Southern California pulled the plug on just 30 customers to prevent power lines and other electrical equipment from sparking a blaze. (JAE C. HONG / AP)

Firefighters in Southern California reported little headway on Tuesday against two explosive, wind-whipped wildfires that forced the evacuations of tens of thousands of residents and badly injured two crew members on the front lines.

Wildfires this year have ravaged California, scorching more than 616,500 square km - equivalent to the land mass of the state of Hawaii - since the start of the year, with 31 lives lost and thousands of homes destroyed

Howling Santa Ana winds, blowing hot, dry air from the desert, had put much of the fire-ravaged state under red-flag warnings and helped quickly spread two blazes in Orange County that erupted on Monday.

But by midday on Tuesday, winds that had accelerated the Orange County fires had settled down to 8 to 16 kilometers per hour, with occasional gusts of up to 32 kph, the National Weather Service said. Winds were forecast to weaken further and remain light for at least the next two days, it said.

More than 750 firefighters using 14 helicopters managed to contain only 5 percent of the Silverado fire, which grew overnight to 4,500 hectares from 2,900 hectares late on Monday, the Orange County Fire Authority said.

Two firefighters were critically injured fighting the blaze, with second- and third-degree burns over much of their bodies, the OCFA said.

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A firefighter prepares to put out hotspots while battling the Silverado Fire, Oct 26, 2020, in Irvine, Califorlia. (JAE C. HONG /AP)

The blaze, which was not immediately blamed for any property loss, may have been started by equipment owned by Southern California Edison, the utility company said.

“It appears that a lashing wire attached to a telecommunications line may have contacted SCE’s power line above it, possibly starting the fire,” a company spokesman said.

The incident is being investigated, he added.

As a precautionary measure, the utility said on Tuesday that it had cut power to nearly 19,000 homes and businesses, including about 1,270 in Orange County.

Gusting winds carry smoke from the Silverado Fire into residential areas, Oct 26, 2020, in Irvine, California. (JAE C. HONG / AP)

The fire in the foothills of the Santa Ana Mountains south of Los Angeles prompted officials to order more than 90,000 residents to leave their homes on Monday in and around the city of Irvine, officials said. The Irvine Unified School District closed schools for the day.

The other Orange County blaze, the Blue Ridge fire, which broke out later near Yorba Linda, also spread quickly overnight, charring 6,150 hectares by Tuesday morning, OCFA said.

Some 1,000 firefighters had yet to set up any containment lines around the blaze, which damaged 10 homes and is threatening thousands more, OCFA said.

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A helicopter flies away after dropping water over the Blue Ridge Fire burning along the 71 state highway, Oct 27, 2020, in Chino Hills, California. (JAE C. HONG / AP)

No injuries have been linked to the Blue Ridge fire so far, but authorities ordered residents of more than 8,700 homes in Yorba Linda, Chino Hills and Brea to evacuate.

Wildfires this year have ravaged California, scorching more than 616,500 square km - equivalent to the land mass of the state of Hawaii - since the start of the year, with 31 lives lost and thousands of homes destroyed.