Firefighters were ambushed by a gunman while responding to a brush fire in Coeur d'Alene, Idaho, Kootenai County Sheriff's Lt. Jeff Howard told ABC News.

The incident unfolded after a small but growing brush fire broke out on Canfield Mountain Sunday afternoon.

When fire personnel responded to the blaze, they started getting shot at by an unknown person in the woods, Howard said.

Law enforcement is investigating whether the fire could have been intentionally set in order to lure first responders to the scene, Howard added.

The scene is considered an active shooter situation and a shelter-in-place order has been issued for Canfield Mountain Trailhead and the surrounding area.

This is a developing story. Please check back for updates.