APPLEGATE, Calif. » Firefighters on the ground and in the air battled five grass fires totaling about 380 acres that forced the closure of eastbound Interstate 80 northeast of Sacramento, burned at least one home and threatened dozens more Wednesday.

One home in the unincorporated 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.

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

The tankers were private planes contracted by the U.S. Forest Service with CalFire’s tanker fleet grounded after Tuesday’s crash that killed a pilot near Yosemite National Park.

The cause of the fires, first reported about 1:30 p.m., remains under investigation, said Daniel Berlant, spokesman for CalFire.

"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."

Interstate 80’s eastbound lanes were closed for several hours, and Cal Fire ordered the evacuation of homes on a half-dozen streets in the Weimar area, Berlant said. Officials planned to reopen a lane with the fire 10 percent contained, he said.

Placer County Sheriff deputies helped with the evacuations, Martis said.

The fire was burning about 40 miles northeast of Sacramento along I-80, a key connector between Northern California and Nevada.