A wildfire scorching two counties in California has burned more than 41,400 acres and is threatening thousands of homes and structures, officials said Sunday.

The Mosquito Fire in the foothills east of Sacramento threatened more than 5,000 structures in Placer and El Dorado counties as an increase in winds continued the fires spread, CAL Fire said.

"Firefighters have been working diligently to build control lines along the area of Foresthill Road and out in front of the head of the fire toward the north and northeast," fire officials said. "A spot fire in the area of Chicken Hawk occurred yesterday and firefighters were able to contain that fire with the help of dozers and aircraft today."

Evacuation orders were in place for 11,000 residents in nearby communities, SFGate reported.

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firefighters fighting fire

Fire officials said 1,700 personnel and 32 crews were among the resources being used to fight the fire. (CAL Fire)

CAL Fire said 1,700 fire personnel were battling the blaze, was 10% contained as of Sunday.

The flames ignited on Tuesday, blanketing the region in plumes smoke.

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While the wildfire’s cause remained under investigation, Pacific Gas & Electric said unspecified "electrical activity" occurred close in time to the report of the fire on Tuesday.

The Associated Press contributed to this report.