At least two firefighters killed by 'sniper fire' while battling Idaho blaze, sheriff says

Armoured police vehicles were seen driving towards Canfield Mountain, in the small town of Coeur d'Alene. (Reuters: Young Kwak)

 At least two firefighters who were called to respond to a blaze have been killed when they were ambushed by barrages of sniper fire from at least one suspect over several hours in north-western Idaho, according to a local sheriff.

The Kootenai County Sheriff's Office said crews responded to a fire at Canfield Mountain, near Coeur d'Alene, at 1:21pm, local time, on Sunday and gunshots were reported 40 minutes later.

Sheriff Bob Norris told reporters officials didn't know if anyone else was shot.

"We don't know how many suspects are up there, and we don't know how many casualties there are," he said.

"We are actively taking sniper fire as we speak.

"We are prepared to neutralise this suspect who is currently actively shooting at public safety personnel."

Sheriff Norris said it appeared the sniper was not barricaded inside of a house, but appeared to be hiding in the rugged terrain while "blending in with their surroundings" and using a high-powered rifle. He said he had instructed deputies to fire back.

They were "well-prepared," he added, saying authorities did not know if there was "one, two, three or four" shooters.

“I’m hoping that somebody has a clear shot and is able to neutralise, because they’re not at this point in time showing any evidence of wanting to surrender,” the sheriff said.

The Kootenai County Sheriff's Office said it was responding to an active shooter incident.

Sheriff Norris told reporters people were still coming off the mountain late on Sunday afternoon, and it "would be safe to assume" that others were still up there.

Idaho Governor Brad Little said in a post on social media that "multiple" firefighters had been attacked.

"This is a heinous direct assault on our brave firefighters," Governor Little said.

"I ask all Idahoans to pray for them and their families as we wait to learn more."

The sheriff's office in the neighbouring Shoshone County said on Facebook that authorities were "dealing with an active shooter situation where the shooter is still at large".

US Department of Homeland Security Secretary Kristi Noem had been briefed on the shooting, according to reports from the US-based ABC News.

A Kootenai County Emergency Management Office alert asked people to avoid the area around Canfield Mountain Trailhead and Nettleton Gulch Road, about 6.5 kilometres north of downtown Coeur d'Alene.

Sheriff Norris said the fire that authorities had been responding to was still burning.

"It's going to keep burning," he said.

"Can't put any resources on it right now."

Law enforcement is investigating whether the fire could have been intentionally set in order to lure first responders to the scene, according to Kootenai County Sheriff's Lieutenant Jeff Howard.

Earlier, local fire chief Pat Riley described himself as "heartbroken" by the attack.

He told local TV station KHQ that no evacuations had been ordered, even though the fire was still burning.

When asked if there was a concern about the fire spreading, he told KHQ: "Yes there is. To what extent, I can't say, because we can't get people to where the fire's at."

He said he did not know how many casualties there were, but that they were "all fire service personnel".

Coeur d'Alene is a city of 55,000 residents near the border with the state of Washington. 

Canfield Mountain is a popular hiking and biking area on the outskirts of the northern Idaho city, covered with trees and heavy brush and crisscrossed with trails.