Authorities said the Mudd Fire continued to threaten residents near the small Elmore County town of Mayfield, where 200 homes were under evacuation orders. Firefighters were trying to stop the fire's progress, the U.S. Forest Service said.
The Pony Complex of fires experienced "extreme" behavior and grew to cover roughly 150 square miles, the Forest Service said. Officials said Sunday that about 200 firefighters and support staff were fighting the fire complex, which was just 10 percent contained.
The Elmore County Sheriff's Department was also asking some residents between Pine and Featherville to evacuate. Evacuations also remained in place near Prairie.
The nearby Elk Complex of fires was nearly as large with no containment as 220 people staffed the blaze.
Both fires, southeast of Boise, started last week by lightning and were listed by the Forest Service as having a high growth potential with temperatures in the low 90s.
"This morning it is reported that the lodge in Falls Creek and approximately 20 structures have not been damaged by the fire, but it is believed there is structure loss further up the drainage," said Boise National Forest spokesman David Olson. "The Lester Creek Guard Station has not been damaged."
The American Red Cross said it has opened an evacuation shelter at the Good Council Hall in Mount Home for displaced residents.
A large part of the national forest in the region has also been closed.
Officials said they also continue to battle a series of smaller fires on state land throughout Idaho.