Between 500 and 1,000 residents were told to leave their homes Thursday as a complex of wildfires burned toward the central Oregon community of Camp Sherman.

President Bush took an aerial tour of the fires aboard a Marine helicopter, but the thick smoke blocked the view and its acrid smell filled the cabin. He was scheduled to deliver an afternoon speech on forest policy at Camp Sherman (search), but the event was moved to Redmond because of the fires.

The 4,000-acre fire complex in the Mount Jefferson Wilderness (search) threw up a white-capped plume of smoke that towered over central Oregon. In addition to the Camp Sherman evacuations, residents of Black Butte Ranch, a resort community four miles from the fire, were told they might have to leave, and a 21-mile stretch of U.S. 20 over the Cascades was closed.

"It's a real dangerous fire," said incident commander Mike Benefield from an observation point east of the Santiam summit. "It's going to cover some ground before it's all done."

The fires burned a youth camp Thursday but have apparently not damaged any homes yet. The camp had been evacuated earlier.

The evacuation order issued Thursday affects about 400 homes, said Carol Connolly, spokeswoman with the Central Oregon Interagency Dispatch Center (search). More than 700 campers at campgrounds and retreats had left the area earlier.

Several hundred firefighters are heading to the area to help the 220 firefighters already at the scene, said David Widmark, spokesman for the Northwest Interagency Coordination Center (search). The cause of the fire wasn't immediately known.

In Montana, about 150 families were poised to leave their homes in Lincoln because of two wildfires burning uncontrolled through surrounding forests. Fire crews worked Thursday morning to put protective foam on 120 homes that already were evacuated.

About three dozen large fires are burning in Montana, and the military is being called upon as the situation worsens. About 500 National Guardsmen were expected to begin working Thursday on fires west of Missoula, and another 100 were due to start work on the Lincoln fires by Monday, a fire spokesman said.

The Defense Department said Thursday it planned to call in 560 soldiers from Fort Hood, Texas, to help battle blazes in Montana.

About 2.4 million acres have been charred so far this wildfire season, according to the National Interagency Fire Center. The hot spot now is in the Northern Rockies, but wildfires continue elsewhere in the West.

In Wyoming, a new fire in the Shoshone National Forest (search) southwest of Cody exploded from just 20 acres to 6,000 acres Wednesday, and increased to 10,000 acres by Thursday afternoon. A few dude ranches are in the area, but gusty winds pushed the fire away from the ranches and no evacuations were requested.

The fire is one of several burning between Cody and Yellowstone National Park, but no structures are threatened. The park's east entrance remains closed because of fires next to the road, but the park's four other entrances were open and park facilities were not affected.

A thunderstorm peppered northern Idaho with small fires late Wednesday as firefighters continue to dig suppression lines around several large blazes in the area. Fire officials issued a "red flag warning" that windy weather could fan those blazes even more. Wildfires covered more than 80,000 acres in Idaho, according to the National Interagency Fire Center.