DONNER LAKE -- Workers cutting trees that came in contact with a power line are being blamed for a 100-acre fire near Donner Summit that shut down Interstate 80 for about three hours.

Sierra Pacific Power Co. spokesman Karl Walquist said on Thursday the company, which he declined to identify, had been hired to remove hazard trees from the vicinity of power lines.

Walquist said Sierra Pacific has met with the company to ensure such accidents won't occur again.

The fire broke out shortly before 2 p.m. Wednesday and the interstate was closed a short time later. It reopened about 5:30 p.m. after westbound traffic had backed up for miles.

Hundreds of homes were in the area of the blaze, but no evacuations were ordered and engines were positioned to protect structures.

There were no injuries.

By evening, about 300 firefighters were attacking the blaze with 37 engines, six air tankers, four helicopters and two bulldozers. In early evening, winds calmed.

"That allowed us to get ground crews into the area and attack the fire," fire spokesman Daniel Berlant said.

He would not speculate on a cause. Downed power lines were reported in the area around the time of the fire.

Tractor-trailers parked along the side of the highway. Other vehicles pulled off at the California 89 interchange and used local roads to get around the fire scene.

"I saw everyone else turned around, so I just turned around too," said Lee Vymetal of Reno. "I wasn't going to get through, and if anyone is trying to use westbound I-80, they're not going to get anywhere."