A shelter-in-place order was lifted on Sunday night after two firefighters were killed earlier in the day and another was wounded when they were ambushed by sniper fire while responding to a blaze in a northern Idaho mountain community.

The order was lifted after a tactical response team discovered the body of a man with a firearm nearby, the Kootenai County Sheriff’s Office said. Officials did not release his name, nor did they say what kind of gun was found.

Firefighting crews endured a barrage of gunfire over several hours that the governor called a “heinous” assault.

Sheriff's officials said crews responded to a fire at Canfield Mountain just north of Coeur d’Alene in the early afternoon, and gunshots were reported about a half hour later.

Sheriff Bob Norris earlier said officials were not immediately sure how many people were shot and deputies were “actively taking sniper fire as we speak”.

Three victims were brought to Kootenai Health, said the hospital's Kim Anderson.

Two were dead on arrival and the third was being treated for injuries, Anderson said. The wounded firefighter’s condition was not known. (AP)