Wildfires burned mobile homes, closed highways and forced evacuations from a popular wilderness park Saturday as firefighters worked through scorching heat to contain blazes throughout the West. No injuries were reported.

Lightning sparked about a dozen fires that had charred about 55 square miles in remote northern Nevada, where temperatures in Elko were expected to reach 98 degrees on Saturday.

The two biggest fires broke out Friday in Elko County. One had burned 36 square miles, or 23,000 acres, along the Idaho border, said Mike Brown, a spokesman for the U.S. Bureau of Land Management. It was 10 percent contained Saturday, officials said.

The other fire had blackened 11 square miles, or 7,000 acres, about five miles southwest of Carlin. It burned two mobile homes and several smaller structures, and shut down a section of Interstate 80.

"Both fires burned actively last night and showed extreme fire behavior," said Sam Hicks, fire management officer for the Nevada Division of Forestry.

The interstate was closed for six hours overnight as the blaze neared the highway, fire information officer Tracie Winfrey said. On Saturday morning, the fire was 40 percent contained.

In California, three wildfires ignited by lightning spread quickly Saturday morning through a wilderness park, officials said.

More than 400 firefighters were battling the blaze, which has consumed 17,000 acres of the 2 million-acre Inyo National Forest, forest spokeswoman Nancy Upham said Saturday. Firefighters were searching for and evacuating an unknown number of day hikers and overnight backpackers.

A section of Highway 395, which runs along the eastern spine of the Sierra Nevada mountain range, was closed, and many smaller roads leading from the highway into the mountains were also closed. Campgrounds and a lodge had been evacuated, Upham said.

In Southern California, a wildfire burned into a wilderness area of Los Padres National Forest, threatening some campgrounds and showing no sign of slowing down as it moved through tinder-dry chaparral in Santa Barbara County. The fire was heading east and threatened some campgrounds and the historic Manzana schoolhouse, a century-old wooden building, fire spokesman Andy Yamamoto said.

The fire was burning in a steep, remote area in brush and oak woodlands that had not seen flames for about 40 years, Yamamoto said.

The fires in the West have been fueled by an oppressive heat wave that has been felt throughout the region for days, but that has now eased a bit in places. Still, forecasters predicted little relief in the days ahead for a region where many cities have baked in triple-digit temperatures.

Dozens of firefighters battled a blaze near Rulison, Colo., that had destroyed a house and two other buildings. No size estimate was available, but an official said the blaze appeared to have moved at least two miles.

Las Vegas had been cooling since Wednesday, when it tied a record with a high of 116. Slightly overcast and a mere 107 degrees at noon Saturday, the city felt cool to some desert dwellers.

"This is fine to us," said Patti Johns, 52, a tourist visiting with her husband from Phoenix. "I'll take this over winter anytime."

But in Idaho, residents of the Wood River Valley and possibly Boise were warned they could see electrical failures in the middle of the heat wave. A wildfire damaged dozens of power poles on Friday and caused one to fall on a substation and destroy a transformer, said Jeff Beaman, a spokesman for Idaho Power.

The damage could cause rotating outages and residents were asked to reduce their power usage so the utility could meet demand, Beaman said.

In Montana, it was even too hot to fish.

Yellowstone National Park and state fisheries managers asked anglers starting Saturday not to fish on some Montana rivers between noon and 6 p.m. due to drought and scorching weather. Water temperatures in some lower-elevation rivers have reached 73 degrees in recent days, conditions that can stress and even kill fish, the National Park Service said Friday.

Park officials hoped the voluntary restrictions would prevent mandatory closures later in the season.

Associated Press writers Rachel Konrad in San Francisco and Keith Ridler in Boise, Idaho, contributed to this report.