01/30/2016 12:38 EST | Updated 01/30/2017 00:12 EST

5 killed in B.C. avalanche: chances of surviving plummet after 10 minutes

MCBRIDE, B.C. — A leading expert says that after 10 minutes of being trapped in an avalanche, chances of survival drop dramatically as the snow hardens like concrete.

Five snowmobilers died Friday in a major avalanche near the interior community of McBride, B.C.

Pascal Haegli is Simon Frasier University's research chair in avalanche risk management. He says it's nearly impossible to dig yourself out of an avalanche once you've been buried, and that without proper rescue equipment, chances of survival nearly disappear.

He says that people should not rely on search and rescue crews in the event of an avalanche.

Karl Klassen, of Avalanche Canada, said Friday that the avalanche appears to have been human-triggered, but he did not elaborate.

Haegli says that he hasn't heard exactly what happened in this case, but that human-triggered avalanches can occur when people disturb different layers of snow, called snowpack. For instance, if a thin layer of icy snow sitting on top of looser snow is disturbed, it can cause all the snow to tumble down.

He says avalanches can also be purposefully triggered using explosives, to clear the way for skiing or driving.

The Canadian Press