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Boy Scouts and hikers were airlifted from a Utah canyon as a wildfire swept through a campground and destroyed a nearby motel, authorities said Friday.

"They'd had to get up in some real rough, rocky area to get away from the fire, so it could have been bad. But with quick work by the helicopters, they were able to get out," said Bert Hart, a spokesman at the U.S. Bureau of Land Management. Eighteen Scouts and hikers had to be rescued.

The fire started Thursday at a campground 85 miles south of Salt Lake City, the U.S. Forest Service said Friday. By Friday, 20 square miles, or more than 13,000 acres, had burned, and all campgrounds and cabins were evacuated along a scenic road in Uinta National Forest.

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Utah was so dry that some communities banned traditional July 24 fireworks that members of the Church of Jesus Christ of Latter-day Saints normally shoot off to celebrate the 1847 arrival of Mormon pioneers in the Salt Lake Valley.

The United States' firefighting preparedness is at its highest level because of bone-dry conditions in the West and the number of fires.

More moderate weather Thursday helped firefighters contain 13 large fires burning in the West, and others are expected to be contained in coming days, according to the National Interagency Fire Center.

Almost half of the 72 large fires burning nationally are in Nevada and Idaho.

Near the Nevada state line, a blaze that burned nearly 200 square miles threatened the town of Murphy Hot Springs and its 50 homes, said Brock Astle with the U.S. Bureau of Land Management.

Residents were told to leave because of fear they wouldn't have a way to escape if the fire spread, similar to the evacuation of the small town of Jarbidge, nestled in a tight canyon near the Idaho line.

"The bottom line is, if the fire goes into the canyon, the likelihood that it can be stopped is slim to none," Elko County Sheriff Dale Lotspeich said.

Crews contained a fire that had burned 14 square miles near the Idaho National Laboratory, U.S. Department of Energy officials said.

Roughly 700 workers at the lab's Materials and Fuels Complex were told to stay home Thursday because of the blaze, and the Idaho State Police intermittently closed U.S. Highway 20 to give crews room to strengthen a fire break designed to keep the fire from jumping the highway. The highway was reopened Thursday night.

"Over the last four days we've had over 1,400 new fires start" around the West, said Ken Frederick, a spokesman for the Boise-based National Interagency Fire Center. Though many of the fires were caught and contained while they were still small, a number of them have grown substantially, he said.

The U.S. Bureau of Land Management put Nevada on the top of its priority list. The federal designation brought in resources from neighboring states to assist firefighters, who acknowledged they were stretched thin by the blazes that stretch across most of the northern third of Nevada.

Firefighters were getting a handle on a wildfire that had threatened hundreds of homes on the edge of Reno. It was about 15 percent contained and some of the 600 firefighters on scene were being dispatched to other fires.

The nation's firefighting preparedness was raised to its higher level, allowing fire managers to request help from international crews, although Frederick said none had been requested so far.

In Northern California, overnight downpours helped crews battling nine fires burning about 17 1/2 square miles near the Oregon border, where flames came within a half-mile of more than 300 homes in and around Happy Camp.

"It did slow the fires down some, but the forecast doesn't show any rain in the near future," U.S. Forest Service spokesman Dwane Lyon said. "We're anticipating that we're going to be fighting aggressive fire again this weekend."

The largest wildfire in Oregon, near Riley, had grown to more than 211 square miles and was threatening a handful of homes, officials said.

In Southern California, a 48-square-mile wildfire had slowed and an evacuation order for about 50 homes in its path was canceled, although residents were urged to be ready to flee if flames made a sudden run.

The fire in Los Padres National Forest was still dangerous but its eastern movement was reduced as it left steep slopes and crept into flatter terrain, U.S. Forest Service spokeswoman Helen Tarbet said.

"The weather is kind of cooperating," Tarbet added. "It's cooler than it has been and it's really not expected to move a whole lot."

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