India, July 1 -- Just hours before opening fire on firefighters in northern Idaho, Wess Val Roley, the 20-year-old suspected gunman, posted an ominous Instagram story.

The image, shared to his Instagram Stories and since deleted, shows Roley wearing a balaclava with what appeared to be coal-like soot smeared on his face. He had a belt of rifle shells strapped across his chest. The post was accompanied by the eerie lyrics of a Bjork song: "I'm going hunting."

That spine-chilling post was made shortly before officials say Roley intentionally started a fire on Canfield Mountain near Coeur d'Alene and ambushed first responders. Two firefighters were killed and another critically injured in the shootout that followed.

"It's clear to me that...