APPLEGATE, Calif. (AP) — A series of small wildfires that broke out along Interstate 80 some 40 miles northeast of Sacramento burned one home, threatened dozens more and brought the partial shutdown of the key highway between Northern California and Nevada.

The wildfires Wednesday grew to a combined 380 acres, the California Department of Forestry and Fire Protection said in a statement.

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

In the I-80 area fires, one home in the small community of Applegate in Placer County was destroyed by the blazes while crews were searching for more possible destruction, said Lynne Tolmachoff, spokeswoman for the California Department of Forestry and Fire Protection.

It was not immediately clear what caused the fires, CalFire spokesman Daniel Berlant said.

“We don’t know the cause, but any time we have multiple fires that started in the same area along the roadside, that tells us we probably have human activity,” Berlant said. “It does not necessarily point toward arson, but our investigators are working to determine that.”

At least two callers reported seeing several car tires burning along the interstate’s eastbound shoulder, California Highway Patrol officer Mike Martis said.

I-80’s eastbound lanes were closed for several hours. A single lane was opened once the blaze was 10 percent contained, CalFire said.

About a dozen aircraft including air tankers and helicopters were making drops of fire retardant over the area, where a handful of homes dotted heavily forested foothills. About 80 homes were under threat, and six residential streets were under evacuation orders, CalFire said.

Meanwhile, the wildfire in Yosemite had grown to 252 acres by Wednesday afternoon, a day after it broke out, though some of the smoke had lifted, said park fire information spokeswoman Jennifer Wuchner. Electricity was out in Yosemite Valley because power lines near the crash site were shut down, and park facilities were using generators, she said.

Some 60 homes in the community of Foresta were under evacuation orders.

Tolmachoff said that the air tanker crash occurred on Tuesday as four CalFire aircraft, including three tankers, were fighting the blaze as it climbed a steep canyon wall north of the Merced River. The body of pilot Geoffrey “Craig” Hunt was recovered Wednesday.

The department had helicopters, guide planes and aircraft from other agencies to take on the blaze at Yosemite and others in the state, but the S-2T tankers that were grounded indefinitely Wednesday can carry 1,200 gallons apiece of fire retardant and are considered an essential resource for dealing with wildfires before they spiral out of control.

“These are our initial attack aircraft,” Tolmachoff said.

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