A series of wildfires are spreading throughout California as the state battles one of the worst heat waves in its history. 

On Wednesday, the wildfires were burning out of control in Southern California and the Sierra Nevada, forcing evacuations.

Fairview Fire in California

Crews battle the Fairview Fire in Riverside County. (CAL FIRE/Riverside County Fire Department)

The deadly Fairview Fire grew to nearly 10,000 acres near the city of Hemet, which is about 80 miles southeast of Los Angeles. Firefighters said it was only 5% contained. 

Cal Fire Battalion Chief Josh Janssen told a briefing "open fire on all sides of the fire still threatening several communities."

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The Fairview Fire erupted Monday amid triple-digit heat and spread ferociously, killing two people who were found in a vehicle, severely burning another person while destroying seven structures and damaging several others.

"Unfortunately we aren't able to positively identify the victims at this time. But we do believe that they were from the same family," sheriff's Sgt. Brandi Swan said. "It appears as though the two victims that were found inside the vehicle were trying to flee from the fire."

The injured person was identified only as a woman. Swan said she was expected to survive. 

The cause of the fire was under investigation. Southern California Edison notified the California Public Utilities Commission that unspecified "circuit activity" occurred close in time to when the fire was reported.

Fire in Hemet, California

Wind whips embers from a burning tree during a wildfire Tuesday, Sept. 6, 2022, near Hemet, Calif.  (AP Photo/Ringo H.W. Chiu)

About 35 miles to the north, smoke loomed over ski runs in the San Bernardino Mountains as the Radford Fire fed on stands of timber south of the Big Bear Lake resort region.

The blaze spread over 1.5 square miles since being spotted by a U.S. Forest Service helicopter crew Monday afternoon. It was just 2% contained.

In the Sierra, evacuation orders and warnings were in place in Placer, and El Dorado counties as the day-old Mosquito Fire grew to nearly 2 square miles with zero containment.

Another blaze in Northern California, the Mill Fire, erupted in the Northern California town of Weed on September 2 and has since killed at least two people. 

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Roseburg Forest Products Co., a wood products company, said Wednesday it is investigating whether the Mill Fire was caused by the possible failure of a water-spraying machine used to cool ash at its veneer mill. 

Although the investigation was incomplete, the company was planning to provide up to $50 million for a community restoration fund to assist residents with temporary shelter, medical supplies and treatment, transportation, clothing, food and water, and child care services.

Hundreds of people fled as the fire spread, destroying 107 structures, and damaging 26 others. The blaze eventually grew to more than 6 square miles. The fire was 65% contained Wednesday, with minimal activity.

Near the Oregon border, the Mountain Fire – which began on September 2 – covered more than 18 square miles of Siskiyou County and was 30% contained. 

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The fires come amid a brutal heat wave that has pushed electricity demand in California to its limits.  The state’s grid operator warned residents this week to prepare for the possibility of rolling blackouts. 

The Associated Press contributed to this report.