A group of campers had to be rescued by helicopter, after a colossal landslide of rock and snow left them trapped in what geologists say is one of the most dangerous valleys in Canada.

The two-kilometre-wide landslide blocked a creek near Meager Creek Hot Springs in southern British Columbia at around 7 a.m. local time, and prompted an evacuation alert for about 5,000 residents in the area.

The slide also swallowed an access road that left 13 campers marooned in the wilderness. Eight were airlifted to the nearby village of Pemberton, the RCMP said, while five chose to stay behind. There were no injuries.

"We got them out and we were done with the evacuation process around lunchtime, and now we're just triple-checking, confirming that everyone is safe and sound and everyone is accounted for," said Sgt. Shawn LeMay of the RCMP.

The slide blocked Meager Creek, causing water levels to rise and sparking the evacuation alert.

"Local residents in the upper Pemberton valley are concerned about, is there water pooling up there where the landslide occurred? If so, will it break through? Where will it overflow?" said regional district information officer Leslie Lloyd.

John Clague, a geology professor at Simon Fraser University, said hot weather may have melted snow and ice on a glacier above the creek, causing the earth to give way.

Emergency workers are investigating to see whether they will close any roads or issue additional public-safety warnings for the area, which lies about 250 kilometres northwest of Vancouver.

Premier Gordon Campbell said he was relieved there were no injuries.

"It looks like there's been no personal injury or loss of life, which of course is the first thing that you're always concerned about," Campbell told The Canadian Press from the premiers meeting in Winnipeg.

"I think we're all concerned about what the impact may be on Pemberton and that area, so we have emergency personnel up there now and the RCMP up there now. We'll try to do everything we can to try to make sure that there's no further damage."

A landslide struck the same area 12 years ago, creating an 800-metre-wide lake.

With a report from CTV British Columbia's Leah Hendry