A mountain biker who worked for the US Forest Service has been killed by a grizzly bear near a Montana national park.
Law enforcement officer Brad Treat, 38, of West Glacier, was killed on a trail in the Halfmoon Lakes area of the Flathead National Forest, just outside Glacier National Park, about three miles from the park entrance at West Glacier.
Flathead County sheriff Chuck Curry said Mr Treat was cycling with another person when they surprised the bear, which knocked Mr Treat off his bike.
The second rider left to get help and was not injured.
Authorities found Mr Treat's body at the scene, but not the bear.
The area has been closed off and wildlife and law-enforcement officers are hunting for the grizzly.
"Brad was an integral member of our area law enforcement team and a friend to us all," Sheriff Curry said.
Mr Treat grew up in nearby Kalispell, where he was a talented distance runner at high school, his former coach, Paul Jorgenson, told the Flathead Beacon newspaper.
"He was a really good runner but he was also a kind-hearted person who cared about people," he said.
Grizzlies in the Lower 48 states have been designated a threatened species since the 1970s, but their numbers are increasing and so are conflicts between humans and bears.
The grizzlies in the Glacier area among about 1,000 bears in the Northern Continental Divide Ecosystem, which also includes the Bob Marshall Wilderness south of the park.
At least 700 more grizzlies live in and around Yellowstone National Park, about 360 miles south of Glacier.
Six people have been fatally mauled by bears in the Northern Rockies since 2010, but those deaths were mainly in the Yellowstone area.
Glacier officials say there are usually one or two non-lethal encounters between bears and humans each year inside the park.
Before Wednesday, there had been 10 bear-related human deaths in Glacier since the park was created in 1910.
The last was in 1998, when three bears killed and partially ate a park vendor employee while he was hiking.
In the most well-known Glacier attacks, bears killed two people in different parts of the park in a single night in 1967.
Those attacks became the subject of a 1969 book by Jack Olsen, Night Of The Grizzlies, and later a documentary by the same name.