APPLEGATE, Calif. (AP) — Fire crews are fighting to prevent a series of small wildfires from getting into a canyon along Interstate 80 in Northern California where dry brush and trees could cause it to take off.

California fire officials say crews fighting the small fires about 40 miles northeast of Sacramento are relying on air tankers from the U.S. Forest Service, helicopters and ground crews.

California’s fleet of 22 air tankers were grounded Wednesday after one of the planes crashed while battling a separate wildfire in Yosemite National Park, killing the pilot.

The fires are threatening 1,000 structures around the community of Applegate in Placer County, with many homes under mandatory evacuation orders.

The fires had burned through 420 acres since beginning Wednesday. It was 20 percent contained.

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