Eight snowmobilers are unaccounted for and feared dead near Fernie, B.C., after an avalanche buried some of them — and a second avalanche buried their would-be rescuers.

In a statement issued late Sunday, the RCMP gave this sequence of events:

• The first avalanche caught part of a group of seven snowmobilers in the Harvey Pass area, a popular back-country snowmobile destination about 40 kilometres south of Fernie.
• A second group of four riders heard their cries and came to help members of the first group dig out their fellow riders.
• They located one rider, but as they were digging him out at a depth of about three metres, a second avalanche buried the entire group, all of whom were wearing avalanche beacons.
• Two of the buried riders managed to rescue themselves in about 20 minutes and then used their avalanche beacons to locate a third buried rider, whom they rescued after another 20 minutes of digging.
• The three survivors assessed their surroundings in a large bowl with massive cornices ready to come down. Based on the risk of a third avalanche, they began walking out.

The RCMP statement, which described the situation as a tragedy, said all 11 riders involved are males from the nearby town of Sparwood. It did not give their names or ages.

A helicopter sent to the scene picked up two of the three known survivors, while Fernie Search and Rescue personnel rescued the third, the statement said. All three sustained minor injuries.

Jennifer Henkes, a communications officer with B.C.'s Interior Health Authority, said at least some of the others are believed to have died.

"I've heard that there are fatalities, yes," she told CBC News. "I don't know how many."

She told the Canadian Press that the health authority "would like to extend its deepest condolences to the victims' families during this very difficult time for them in the Elk Valley."

Three people were taken to hospital, she said, with two discharged Sunday and one remaining, and in stable condition. "We do have one survivor in the Elk Valley Hospital. That person is being kept overnight for observation."

The avalanches struck between Sparwood and Fernie in B.C.'s Elk Valley, about 300 kilometres southwest of Calgary.

The Canadian Avalanche Centre, based in Revelstoke, said there were reports of avalanches in the area all day.

James Floyer, an avalanche forecaster at the centre, noted there has been significant new snowfall and a warming period, which have combined to overload the snowpack.

In an alert posted on its website Sunday afternoon, the centre said:

"Mountain conditions, especially around Fernie and the Lizard ranges, have changed and we're now seeing avalanches starting to affect this region. Soft slabs are building at all elevations, and these will become more reactive to human-triggering, and bigger, over the coming days.

"People are keen to get out, and have time to do so over the holiday period, but don't let your enthusiasm, or that of your friends, carry you to places you'll regret later on.

"Unstable conditions will likely persist for a while into the future. Knowing when to back off and when to let 'er loose is the mark of a wise backcountry traveller — thumb off the throttle is a good move right now."

With files from the Canadian Press