BOISE, Idaho (AP) — Firefighters are trying to stop a wildfire from reaching a popular hot springs resort area with buildings dating to the late 1800s.

Fire spokesman Jim Mackensen said Wednesday that nine fire engines are positioned at Burgdorf Hot Springs and that a camp for some 300 firefighters is set up nearby. "There's a large presence up there, believe me," he said.

Burgdorf Hot Springs is about 25 miles (40 kilometers) north of the vacation area of McCall, Idaho. An answering machine at Burgdorf Hot Springs said the resort was closed because of an evacuation and refunds were being offered to affected guests.

A major concern, Mackensen said, are predicted thunderstorms with strong winds that could carry embers miles ahead of the wildfire that's about 3 miles (5 kilometers) from the hot springs.

Adding to that concern is that the lightning-caused wildfire that started Sunday is burning in subalpine fir, which is known for producing embers that produce new fires miles away.

About 400 personnel are assigned to the 350-acre (140-hectare) blaze burning in heavy timber in the Payette National Forest. The fire grew about 200 acres (80 hectares) late Tuesday as winds kicked up and temperatures rose.

Helicopters and fixed-wing aircraft, including a DC-10 air tanker, have been fighting the blaze as well as a pair of water scooping aircraft getting water from nearby Lake Cascade. Mackensen said firefighters have an aggressive strategy.

"This is a full-suppression fire, meaning we are working direct right on the edge of the fire," he said.

Meanwhile in southern Idaho, firefighters are battling a 110-square-mile (285-square-kilometer) wildfire burning in brush and grass about 14 miles (23 kilometers) south of Hammett.

Fire spokeswoman Kelsey Brizendine said Wednesday there's no containment, but progress was being made.

"Right now it sounds like most of the forward progression has been slowed or stopped," she said. "But we do have thunderstorms predicted for later today."

The U.S. Air Force's Saylor Creek Range Complex is within the fire perimeter, and the Air Force has supplied a fire engine to help. The cause of the fire that started Tuesday is unknown.

Southern Idaho has had numerous large grass and brush fires over the last decade as fire-prone cheatgrass, an invasive species that relies on fire to spread, has taken over much of the region.

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