Fires Raze 100 Homes in Northwest : Disaster: Winds gusting to over 60 m.p.h. fan blazes in Washington, Idaho and Montana. At least five people are killed, and more dwellings are threatened by flames.

The first turbulent winds of autumn raked across the summer-dry landscapes of eastern Washington, northern Idaho and Montana, igniting firestorms that burned more than 100 homes by Thursday. Still more dwellings were threatened and at least five people were killed.

Measured by property loss, this was the region’s worst fire disaster in at least a half-century, according to Washington state officials. It also was a disaster that authorities have been warning was inevitable as tens of thousands of newcomers migrate to the Northwest to homestead the pine forests and brushlands.

Four separate clusters of fires were reported in eastern Washington, and others were scattered into Idaho and Montana--the result of an unseasonable 45-day dry spell followed by a weather front that streaked across the region Wednesday with wind gusts over 60 m.p.h.

Most of the worst fires were the result of fallen power lines. Dust clouds and unpredictable winds slowed firefighter response to the blazes and kept firefighting aircraft grounded in some areas for up to 24 hours.

According to officials, a fire-retardant tanker aircraft en route from Santa Barbara to help with fire suppression crashed near Missoula, Mont., killing two. A Montana rancher was reported killed trying to protect his property against a brush fire. One pregnant woman in eastern Washington was killed as she tried to flee her burning neighborhood. And a firefighter in Idaho was crushed by a piece of equipment that overturned.

Around the community of Deer Park north of Spokane, Wash., 84 homes, some of them mobile homes, were burned, according to the state Department of Natural Resources, which is coordinating firefighting efforts.

Another 12 homes were lost south of Spokane. Clusters of fires burned to the west of Spokane and in the north-east corner of the state.

In Idaho, 27 separate fires in the northern panhandle of the state claimed at least four mobile homes. Montana authorities said “several” homes were among 25 or more buildings claimed by wild fires.

Winds subsided across the Pacific Northwest on Thursday, but many fires continued to burn out of control, remaining a threat to property. Scores of people were evacuated in the region.

Officials increasingly worry that the northwest’s booming growth makes these kinds of disasters inevitable. East of the coast-range Cascade Mountains, the problem is subdivision growth in forest areas that are prone to violent, wind-driven fires. West of the Cascades, the problem is subdivision growth in flood plains.

“Just 10 years ago, a forest fire was just that--it was a job of protecting a resource. But today, almost anywhere a fire kicks up, it’s immediately a threat to life and property,” said Sandi Snell of the Washington Department of Natural Resources.

Times Researcher Doug Conner assisted with this story.