The nation's wildfire preparedness was raised to its highest level Thursday as dozens of new fires started in the bone-dry West, including one on the sprawling grounds of the Idaho National Laboratory.

The West had been at level four for only a few weeks when officials decided to raise it to level five, effective Thursday.

"It's driven by a couple of things: The number of large fires we have, and also the fires are occurring in several states and in several geographic areas," said Randy Eardley, a spokesman for the National Interagency Fire Center. "The resources we have are being stretched thin."

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The change allows fire managers to request help from additional crews, including from Canada and Australia, and soldiers with National Guard units could be mobilized. About 15,000 U.S. firefighters already were battling nearly 70 fires bigger than 100 acres in 12 states.

The level was raised as dry lightning blasted and sparked dozens of new blazes in Idaho, Nevada, Oregon and Utah. Since Monday, there have been more than 1,000 new fires reported across the West, Eardley said.

He said dry, windy conditions, thunderstorms and temperatures reaching above 100 degrees were forecast to continue across most of the Rocky Mountain area through next week.

A new wildfire that started Wednesday evening on the Idaho National Laboratory grounds quickly swept across nearly 6 1/2 square miles, 4,000 acres, of sagebrush and grassland at the 890-square-mile nuclear research area in the southeast Idaho desert. Its cause was not known, said John Epperson, an INL spokesman.

No INL facilities were in immediate danger, but the lab's 700 employees were told to stay home Thursday.

The fire, on the southeast side of the reservation, had burned within a mile of U.S. Highway 20, and the road was partly closed because of smoke early Thursday.

Fire crews set a backburn to keep the fire from jumping the highway and "that appears to be working," INL spokesman Ethan Huffman said late Wednesday night.

The nearest INL facility is the Materials and Fuels Complex, roughly five miles northeast of the edge of the fire and on the other side of the highway. Huffman described the complex as an area of research in nuclear reactor fuel development.

He said the metal-roofed complex was surrounded by vast sand buffers and the wildfire posed no danger to it, but operations were suspended Thursday.

In Nevada, crews Wednesday battled more than two dozen fires burning across nearly 200 square miles of rangeland and timber in the northern part of the state. One threatened hundreds of homes on the edge of Reno.

The largest wildfire in Oregon, near Burns in the southeast portion of the state, had grown to more than 200 square miles and was threatening a handful of homes, officials said.

And in Utah, two new large fires were reported, in addition to three already burning on about 640 square miles of grass, sage and timber. It was so dry there that some Utah 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.

In Southern California, authorities were trying to stop a 43-square-mile wildfire from spreading toward about 50 scattered homes in Los Padres National Forest in the interior of Santa Barbara County. In Northern California, overnight drizzle helped firefighters battling flames that threatened more than 300 homes in and around Happy Camp in the Klamath National Forest near the Oregon border.

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