Mounties say that the snowmobiler who was killed in an avalanche near Whistler, B.C. this week triggered the slide while highmarking with a friend.

Forty-four-year-old Dennis Leski of Squamish was trapped in an avalanche on Tuesday in the Grizzly Lake area of Powder Mountain, south of Whistler. He was buried in the snow for about 20 minutes before he could be dug out and flown to hospital, where he was pronounced dead.

It was the first sunny day after a big snowfall, and the avalanche risk was considerable when police say Leski and another rider started highmarking -- trying to get as high as possible on a steep slope.

"One of the males turned one way and the other male turned the other and as they were riding down, they triggered an avalanche," Staff Sgt. Steve LeClair told CTV News.

Everyone in the group would have been wearing an avalanche beacon, but people at the scene of the slide said that one of the beacons may have been set incorrectly, throwing off the entire rescue.

Leski had more than 30 years' experience in the backcountry. Nelson Bastien, president of the Powder Mountain Snowmobile Club, described him as an enthusiastic sledder.

"He is probably one of the best around and he is as brave as anybody can be," Bastien said.

He added that it's crucial for backcountry snowmobilers to carry avalanche equipment and practice using it.

With a report from CTV British Columbia's Nafeesa Karim