STANLEY, Idaho -- An avalanche near Smiley Creek killed one member of a group snowmobiling in the Sawtooth National Forest Sunday.
According to the Blaine County Sheriff's Office, the slide happened around 2 p.m. about 2.5 miles up Frenchman's Creek. That's about 40 miles north of Ketchum and 20 miles southeast of Stanley, Idaho.
A short accident summary released by the nearby Sawtooth Avalanche Center says the slide was likely triggered by four snowmobilers. All were buried about one-to-two feet deep in the 1,400-foot slide, which stretched 300 to 400 feet in width.
Sawtooth Avalanche Center Director Simon Trautman says the avalanche happened when the group stopped their snowmobiles and began to walk around near the terminus of a known avalanche path.
"They were standing in a meadow that was also an avalanche path, and I believe they triggered it," Trautman told KTVB.
"One of the tragic things about this accident is that they were being safe, they had decided not to go on any hills, and they were playing in what they consider to be a flat meadow," said Trautman.
The resulting slide started around 9,000 feet in elevation, and cascaded onto the group, burying them where they stood, according to Trautman.
The victims have been identified as 56-year-old Susan A. Swanton and 65-year-old Robert C. Swanton of Sutherlin, Oregon, along with 64-year-old George Gilbert Martin, Jr. and 70-year-old Lesley Dianne Martin, of Bellevue, Idaho.
Authorities say Robert Swanton was able to dig himself out of the avalanche debris after about 45 minutes.
"Afterwards he was able to see some light and he was able to shove his hand up through the surface of the snow and then it took him 45 minutes to dig himself, (out)" said Trautman.
He then noticed the top of his wife's snowmobile helmet nearby and dug her out.
Both were aided by another party of snowmobilers who used avalanche beacons and shovels to help dig out the third victim, George Gilbert Martin, who was found unresponsive and was later pronounced dead after rescuers performed CPR.
Miraculously, the final victim was found alive after surviving complete burial for more than 90 minutes. Lesley Martin was taken to a local hospital for treatment of hypothermia and admitted in stable condition.
"And that is the second remarkable piece of the story is that she was buried for at least an hour-and-a-half and lived," he said.
Members of the Blaine County Search and Rescue Team along with Coroner Russ Mikel later recovered the body of George Gilbert.
The size of the avalanche was estimated at D3, which means it could bury and destroy a car, damage a truck, destroy a wood-frame house, or break a few trees, according to Avalanche.org.
While information is still preliminary, avalanche professionals do believe the deadly incident could easily have been prevented.
Blaine County Sheriff Gene Ramsey said, "The use of avalanche beacons was a critical tool locating the victims involved in this avalanche. We continue to stress that the backcountry is extremely unstable and we strongly encourage people to wear beacons and be properly equipped if they are not going to stay out of avalanche areas."
Avalanche conditions in the backcountry were rated "high" throughout the weekend in the nearby Smoky and Boulder mountains.
Members of the Sawtooth Avalanche Center and Blaine County Sheriff's Office are continuing to investigate the incident.