YELLOWSTONE NATIONAL PARK, Wyo. (AP) _ Residents of two towns on the edge of Yellowstone National Park were warned Friday they might have to evacuate because of a 36,000-acre forest fire, and inside the park rangers shepherded convoys of tourists down roads otherwise closed by fires.

Forest fires also threatened two communities in Oregon, where youngsters at one Bible camp were sent home as a precaution. Numerous fires also charred woodlands in parts of Washington, California, Utah and Idaho, where one fast- moving fire forced firefighters to pull back Friday.

Two additional battalions of U.S. Army troops, about 1,200 soldiers, from Fort Lewis, Wash., were being trained to assist hard-pressed civilian crews, according to officials of the Boise Interagency Fire Center, which coordinates firefighting efforts in the West. About 1,200 men from Fort Lewis already are fighting fires in and near Yellowstone.

Friday's two convoys of up to 350 cars allowed tourists to get from one side of the park to the other in safety, after a ranger drove the route between the park communities of Canyon and Norris to check its condition.

Ranger Mona Devine said notices were posted Thursday night notifying visitors of the convoys. ''They think it's a big adventure. Of course, some of the people are upset,'' she said.

The convoys filed past the 114,000-acre ''North Fork'' fire, one of 10 involving about 400,000 acres of the park.

Just outside the park's northeast entrance, a 36,000-acre blaze in the Absaroka-Beartooth wilderness area in south-central Montana threatened two towns Friday and a fire official said evacuation plans were ready.

''We have about a 30 to 40 percent chance that we would have to evacuate'' Cooke City and Silver Gate, said David Liebersbach, incident commander on the Storm Creek fire.

The southern edge of the fire was about four miles north of Cooke City and a rocky ridge with little vegetation stood between the fire and the town, Liebersbach said.

''But today we have a forecast of high northerly winds and we could have wind-carried embers that would carry as far as one mile out in front of the fire,'' he said.

He estimated that perhaps 500 to 1,000 people might be affected if an evacuation is ordered.

Yellowstone stopped charging its $10 entry fee Wednesday because of the inconvenience fires created for visitors.

But some visitors saw the restricted access in Yellowstone as a blessing.

''I kind of enjoy being alone in Yellowstone at the height of the tourist season,'' said Melanie Simcoff of San Francisco. ''This is nice, actually, and they say we're here at a very historical moment in the park's history.''

Park facilities at Grant Village, Lewis Lake, Norris, Canyon, Pebble Creek and Madison remained closed Friday.

The park's west entrance was re-opened Friday morning, although intermittent closures were expected. The only other major roads open in the park included the one from the park's north entrance to Mammoth and Tower; from the northeast entrance at Cooke City to Tower and Mammoth; from Mammoth to Indian Creek; and from the west entrance to Old Faithful, also subject to intermittent closures. The park's south entrance near Grant Village also remained closed.

On Friday afternoon, park officials began discouraging people from leaving through the park's northeast entrance because the road east of Cooke City was closed in case residents of that town have to evacuate.

From the south entrance, the Rockefeller Memorial Parkway leading into Grand Teton National Park also was closed, because of a 21,500-acre fire in the Bridger-Teton National Forest.

Some 1,525 firefighters, including about 600 soldiers from Fort Lewis, battled the 162,700-acre Clover-Mist fire burning in the park and in steep, rugged terrain in the Shoshone National Forest.

Elsewhere, residents of Maxville, Mont., a town of about two dozen households 90 miles southwest of Helena, were told to stand by Friday for possible evacuation as a fire spread to about 7,500 acres of heavy timber overnight, said Palmer Bowen, a fire information officer. Winds pushed the fire away from the town during the day, though, he said.

The fire forced closure of the main road through the area, destroyed a trailer home and two bulldozers and chased fire crews out of a mining camp in the Deerlodge National Forest.

In southwestern Oregon, the lightning-sparked Walker Mountain fire crept within a half mile of a subdivision of about 1,000 people north of Grants Pass. In the northeastern corner of the state, the Ward Canyon fire spread to within a mile of the tiny community of Troy, authorities said.

Both communities were placed on evacuation alert. The Ward Canyon blaze had burned 15 unoccupied structures, mostly hunting cabins.

About 120 second-grade children from the Fir Point Bible Camp were taken to a school about 25 miles north of Grants Pass ''as a precautionary move'' after the Woods Creek fire grew to 500 acres, said Jim Fisher, a state Forestry Department spokesman. He said the children headed home Friday and the fire was 75 percent contained.

Also in the state's northeast corner, the Tepee Butte fire exploded to 18,000 acres of grass and timber by Friday morning from 150 acres Thursday afternoon, and firefighters said it could spread to as many as 80,000 acres.

In western Idaho, swirling winds and dry conditions forced fire bosses to withdraw hundreds of firefighters from the raging Eagle Bar fire near Hells Canyon, which spread to over 3,000 acres along the Idaho-Oregon border.

Thirty firefighters were trapped for an hour in a hotspot and had to use their fire shelters for safety before being airlifted out by helicopter at dawn.