A wildland fire in the Sierra foothills grew to 2,151 acres Friday, forcing the evacuations of 1,650 people as it threatened scores of structures, officials said.

The Trailhead fire started Tuesday afternoon along the Middle Fork of the American River, in steep and hard-to-reach terrain near Todd Valley in El Dorado and Placer counties, roughly 130 miles northeast of San Francisco.

The fire was just 12 percent contained Friday morning and had spread from just 350 acres on Wednesday.

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