Jesse Rutherford was golfing with his brother, cousin and a family friend at the resort when the slide hit at around 4:15 p.m. local time.
"We were just about to tee off on the 16th hole when we saw the trees coming down," he says. "We actually had to jump over the mud to avoid getting caught in it."
RCMP, the local fire department and BC ambulances services arrived on the scene shortly after.
No injuries have been reported, but the resort and several homes in the surrounding area have been evacuated as a precaution.
Geo-technical experts have been deployed to survey the land on the ground and by helicopter.
The incident occurred in an area where water levels typically run high, says Marke Dickson, Director of Sales and Marketing for the Fairmont Springs Resort.
"The difficulty for us is that the resort is split in two by Fairmont Creek," he explains. "There's road access that links those two sections, but they've been taken out by the debris flow."
Dickson says the region saw 10-15 mm of rain on Sunday, which may have contributed to the slide.
Over in Johnson's Landing, RCMP say the body of one of the missing victims has been found, following Thursday's landslide.