World champion US skier Kyle Smaine dies in an avalanche in Japan at age 31

• Champion US skier Kyle Smaine died in an avalanche in Japan on Sunday.
• Smaine was skiing with a group of Americans and Austrians when the avalanche crashed down on them.

US world champion skier Kyle Smaine was killed in an avalanche in Japan on Sunday while backcountry skiing, according to multiple reports.

The professional freestyle skier was 31 years old.

Smaine, a California native, had gone to Japan on a marketing trip for Ikon Pass and Nagano Tourism, according to the Mountain Gazette.

NBC News reported that Smaine went skiing Sunday afternoon in Nagano Prefecture on Japan's Honshu island with two other Americans and a group of Austrians they encountered on the slope.

At least five men were caught in an avalanche that crashed down suddenly on the eastern slope of Mount Hakuba Norikura, a local police spokesperson confirmed to Reuters.

"We heard the crack. We realized it is a big one. We started running and then we got hit," one skier who was with Smaine told the Mountain Gazette.

Smaine's father confirmed to NBC News that he died in the avalanche. One member of the Austrian group, who has not yet been identified, also died, according to the Mountain Gazette.

Kyle Smaine won the halfpipe gold medal at the 2015 Snowboarding World Championships. Fellow athletes paid tribute to the champion on social media after word spread of this death.

Travis Ganong, a World Cup skier and Olympian from the US, wrote on Twitter, "Heartbroken to hear of the passing of my friend... He loved skiing more than anyone I knew, you will be missed."