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Mosquito Fire explodes to 30,000 acres; inferno threatens thousands of structures in Placer, El Dorado counties

Firefighters battle explosive Sierra foothills blaze to save homes and animals
Firefighters battle explosive Sierra foothills blaze to save homes and animals 03:57

VOLCANOVILLE, El Dorado County -- Winds from a massive pyrocumulus cloud, soaring thousands of feet and visible in some parts of the Bay Area, whipped the Mosquito Fire into a raging inferno, driving a wall of flames across the American River and into the small mountain community of Volcanoviile.

Overnight the blaze grew to at least 29,585 acres, had zero containment and was threatening 3,666 structures. The fire is burning in the Tahoe National Forest and now extends into both Placer and El Dorado counties. Evacuations have been ordered in both counties.

On Tuesday, the blaze roared through the mountain community of Michigan Bluff, burning structures and vehicles and forcing residents to flee to safety.

Evacuation maps: El Dorado County | Placer County

Cal Fire: Mosquito Fire Incident - latest information

Mosquito Fire Forces Evacuations In Placer County
Vehicles destroyed during the Mosquito Fire near Michigan Bluff, California, US, on Wednesday, Sept. 7, 2022. A wildfire burning in the Tahoe National Forest exploded Wednesday afternoon prompting evacuation orders near Foresthill. Photographer: Jen Osborne/Bloomberg via Getty Images Bloomberg

Gov. Gavin Newsom declared a state of emergency Thursday for El Dorado and Placer counties due to the rapidly-growing wildfire. 

Cal Fire Placer County operations chief Nolan Hill told a community gathering Thursday night that the strong winds drove the flames thousands of acres in a matter of hours, leaping across the American River near the Oxbow Reservoir ignition point and into Volcanoville.

"It was every bit of 5,000 acres," Cal Fire Amador-Eldorado chief Mike Blankenheim told the gathering of concerned local residents of the wall of flames frightening advance. "It move uphill and ran into Volcanoville. We did have some structures destroyed in there, but it's not the whole community by any stretch...The fire is pushing pretty hard."

Firefighters have taken up defensive positions around the towns of Foresthill, home to about 1,500 people, and Georgetown with a population of 3,000. 

Firefighting strike teams from San Francisco, Alameda County and San Jose have joined the growing army attempting to slow the blaze's advance in the drought-stricken timberland.

"The fire is burning in extremely difficult terrain including steep canyons where directly attacking the fire can be difficult," Cal Fire officials said in a news release.

Firefighters were also dealing with triple-digit temperatures and the uncertain weather conditions whipped up by the massive pyrocumulus cloud.

"It's developing this big pyro-cumulous cloud, almost like an explosion," says UC Davis professor Andrew Latimer. "Very little of the energy had to be evaporating water. Most of it could be combusting the plant materials and spreading the fire."

Weather conditions were not expected to improve Friday, which means the help from these local crews will be critical to protecting life and property.

"These extremely high temperatures can obviously be taxing on the body, especially for the firefighters when they're out working in these conditions," says Captain Robert Foxworthy with CalFire.  

The fire's cause remained under investigation. Pacific Gas & Electric notified the state Public Utilities Commission that the U.S. Forest Service placed caution tape around the base of a PG&E transmission pole but that no damage could be seen. PG&E said unspecified "electrical activity" occurred close in time to the report of the fire on Sept. 6.

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