A wildfire broke out in the North Fork area early Saturday afternoon, located just west of Wapiti on the eastern edge of the Shoshone National Forest. Amid hot weather, it burned through nearly 600 acres by the end of the day.

The Lost Creek Fire was reported around 12:46 p.m. Saturday on the south side of U.S. Highway 14/16/20.  Officials were forced to evacuate two guest ranches — the Bill Cody Ranch and the Rimrock Dude Ranch — while Park County Search and Rescue assisted the Forest Service in rescuing six horseback riders from the area, the sheriff's office said.  No structures have been damaged, Shoshone officials said Saturday night.

Three engines from the U.S. Forest Service, three engines from the Bureau of Land Management plus crews from Park County fire departments were helping batttle the blaze by Saturday evening. As of Sunday morning, 89 personnel  were working the fire. The Powell Volunteer Fire Department was  summoned to the scene at 2:18 p.m. Saturday to provide mutal aid to their Cody area counterparts.

"Multiple aerial resources and additional ground resources have been ordered and are enroute," Kristie Salzmann, a spokeswoman for the Shoshone, said in a Saturday evening news release. Sage Decker of the BLM's Wind River/Bighorn Basin district is the current incident commander.

The Wyoming Department of Transportation  closed U.S. Highway 14/16/20 for several hours in the afternoon, forcing some travelers between Cody and Yellowstone National Park to change their routes. The highway reopened Saturday evening, though forest officials warned  that "this may change as smoke may impede traffic."

Shoshone officials say the cause of the fire is unknown. Updates are being posted on InciWeb and on the forest's Facebook page.

A flight pegged the fire at 250 acres in size as of 4 p.m. Saturday, but when a second flight was conducted overnight, the Lost Creek Fire was estimated to have grown to 591 acres.

It's located about 30 miles west of Cody.