NEPHI, Utah (AP) – A wildfire that may have been started by sparks from a flat tire raced across thousands of acres toward a small town Friday, a day after burning through a campground and motel and forcing rescues.

With a highly skilled team on its way from Florida, 150 area firefighters were battling the 20-square-mile fire against a backdrop of extraordinary heat and drought, with no immediate relief predicted.

“It only takes a cigarette or a match and this stuff will explode,” said Fred Burns, owner of Burns Brothers Ranch RV Resort in Fountain Green, which was nearby but not affected.

The fire was burning toward the tiny community of Indianola, and residents in at least two dozen homes were advised to be ready to leave.

It began Thursday in a private campground in Salt Creek Canyon, 85 miles south of Salt Lake City. The campground was not a total loss, although a motel on site and some vehicles and trailers were burned, the U.S. Forest Service said.

Campgrounds and cabins along a 32-mile scenic road in the Uinta National Forest were evacuated overnight, but a portion reopened Friday. Eighteen Boy Scouts and two hikers had to be rescued by helicopter Thursday from Nephi Canyon.

Emergency calls show that a motorist may have sparked the fire by riding on the rim of a flat tire on a highway that is an access route to the forest, Forest Service spokeswoman Loyal Clark said.

Temperatures hit 100 degrees Friday in many spots. The National Weather Service has already recorded 10 days of 100 degrees or higher in Salt Lake City. The summer average is five days.

Precipitation is more than 4.5 inches below normal. The Salt Lake area went 41 days without any measurable rain before a hundredth of an inch fell Tuesday.

The nation’s firefighting preparedness has moved to its highest level this week because of bone-dry conditions in the West and the number of fires.

Almost half the 72 large fires burning nationally are in Nevada and Idaho. Two tiny towns on the states’ shared border were evacuated Thursday.

The 40 or so residents of Jarbidge, Nev., were ordered to leave because of fears that a nearby 195-square-mile fire could spill into the steep, narrow canyon where the town is located.

A 280-square-mile wildfire crept within a mile of Murphy Hot Springs, Idaho, on Friday, but so far none of the town’s 50 homes has burned, fire managers said.

Firefighters started sprinklers in the yards nearest the fire, said Brock Astle of the U.S. Bureau of Land Management. The mandatory evacuation order imposed Thursday won’t be lifted until at least Friday evening, the sheriff’s office said.

Regular work schedules resumed Friday at the Idaho National Laboratory, where more than 700 workers had been asked to stay home the previous day because of a wildfire. No facilities at the nuclear research site were in danger.

More Montana residents were told to evacuate Friday as a blaze nearly doubled in size to 570 acres north of Wolf Creek. Residents of nearly 60 homes had been asked to leave earlier in the week, but firefighting officials said up to 100 buildings were threatened Friday.

Near Reno, Nev., firefighters were getting a handle on a 4-square-mile wildfire that had threatened hundreds of homes on the edge of town. It was 34 percent contained and some of the more than 700 firefighters assigned to the fire were being sent to battle other blazes.

Firefighters made progress on a large wildfire in Los Padres National Forest near California’s central coast, and an evacuation order for about 50 homes was lifted Friday.

In southwestern Utah, a group of fires that began in Zion National Park spilled into neighboring land. Evacuations were ordered and some structures were threatened, although numbers were not immediately available. The fires have burned 8,000 acres, or 12.5 square miles.