LOS ANGELES, United States, June 30, 2025 (BSS/AFP) - At least two people were killed Sunday when firefighters tackling a blaze were ambushed by an unknown number of gunmen in an ongoing standoff in the northwestern US state of Idaho, the local sheriff said.

A blaze was still raging on the mountainside in Kootenai County, a popular park and hiking area, as law enforcement exchanged gunfire with the shooter or shooters, Sheriff Robert Norris told reporters.

"We now have two deaths. We have an unknown amount of casualties. We still have civilians that are coming off of that mountain.... We are actively taking sniper fire as we speak," he said at a press conference.

The attack was carried out with high-powered rifles, the sheriff said, stressing that the goal of law enforcement was to track the assailant or assailants down and shoot on sight.

The shooter showed "no evidence of wanting to surrender," he continued, adding: "As soon as somebody has a clear shot, I encourage them to take that shot to neutralize the threat."

He said authorities believed the two people who were killed were firemen.

Norris said authorities did not believe the suspects were barricaded inside a building, but were in "heavy brush" and were "blending in with their surroundings."

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

The deputy director of the FBI, Dan Bongino, described it as "an active scene" and said the bureau was sending personnel "to provide tactical and operational support."

Footage from the TV station and a photo published by NBC showed dense white smoke billowing above a hilly, forested area.

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."

Norris and other officials told residents to shelter in place until the standoff was over.

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.

According to the Gun Violence Archive, there have been 189 mass shootings in the United States this year -- defined by the organization as incidents where at least four people are killed or wounded, other than the shooter.

Idaho Governor Brad Little described the attack as a "a heinous direct assault on our brave firefighters."

He said he was "heartbroken" by the attack in a post on Facebook.