Boise National Forest Service officials say the Karney Fire has forced about 80 homes in the area to be evacuated.
Earlier Tuesday, officials had estimated the fire was 15 percent contained, but announced Tuesday night that it had broken containment.
One house was destroyed Monday night by the fire, which officials believe was started by a local volunteer firefighter.
Officials said Tuesday the fire aggressively threatened three homes on the western side of the Wilderness Ranch subdivision, but crews were able to create a fire break that was able to save them.
Fire bosses say the multiple air resources, including helicopters and air tankers, have also been vital to their efforts.
Currently, a voluntary evacuation of about 80 homes in the area in in effect, and the American Red Cross has set up a shelter at Idaho City High School.
Boise County Commissioners have also declared a disaster emergency, which allows them to get state and federal assistance for ten more fire engines to help protect homes.
Officials say the fire has died down Tuesday night, and they are hopeful the work that crews have done will prepare them to contain the fire Wednesday.