Two backcountry snowboarders and a dog were caught in an avalanche on Saturday in Routt National Forest.
One snowboarder died and the other was evacuated to a hospital by helicopter, according to the Colorado Avalanche Information Center (CAIC).
The avalanche occurred in Paradise Bowl, on the west side of Cameron Pass.
Nicki Sartor told 7NEWS she was snowshoeing with her parents some distance away from the avalanche.
"My dad and I literally watched these two individuals go down and the second one was followed by the avalanche. It made my stomach sink and my chest tighten, especially because there was no absolute way we could make it all the way over there in time by foot to help them directly ourselves. But it gave us comfort that at least we witnessed it and could help the emergency teams locate them faster because they knew exactly where to look," she wrote.
CAIC investigators visited the avalanche site on Sunday.