Officials in the state of Idaho, U.S have identified a man believed to have began a bush fire on Sunday and shot at responding firefighters, killing two.

Kootenai County Sheriff Robert Norris named the suspect, who took his own life, as 20-year-old Wess Roley.

A third firefighter was injured in the incident, on Canfield Mountain, outside the city of Coeur d'Alene in the northwestern state.

The sheriff said Roley was originally from California and had lived in various places on the West Coast.

On Sunday, Norris had said the fire had been intentionally ignored, calling it an "ambush."

At least 300 law enforcement officers were deployed to the area.

The victims of the ambush were identified as Frank Harwood, 42, and John Morrison, 52, both veterans of the Kootenai County Fire Department.

The injured officer was identified as 47-year-old Dave Tysdal, who underwent two surgeries in the last 24 hours.

"We have information that he, at one time wanted to be a firefighter, so we don't know if there's a nexus to that desire and what happened yesterday," Norris says.

Serious gun violence is common across the United States, where many states have few barriers to the purchasing of firearms, despite widespread support for greater gun control.

Tere have been 189 mass shootings in the United States in this year, according to the Gun Violence Archive.