Two children, one of whom was on a chairlift at the Crystal Mountain Ski Resort near Kelowna, B.C., when a number of  ski chairs fell seven metres to the ground Saturday, say it's an experience they'll never forget.

Two people are in critical condition and two others sustained minor injuries after an empty chair at the West Kelowna ski hill hit a tower around 11 a.m. PT and fell about seven metres causing other chairs to fall.

Garrick Wiberg says he wasn't on the lift, but his dad helped the victims.

"It's pretty terrifying. I'm still shaking," said Wiberg.

Tyson Hughes was on the lift and had to be rescued.

Crystal Mountain chairlift

IPhone video capture taken just moments after a swinging chair hit a ski lift tower causing the entire line to come down at the Crystal Mountain Ski Resort near Kelowna B.C. Two people were critically injured. Two others sustained minor injuries. (Castanet.net)

"The whole thing [line of chairs] went up, and then it went down. We were up there for about 20 minutes," said Hughes.

Hughes says rescuers slung a rope over the line and brought up "something like a T-bar" to take them off.

Crystal Mountain Ski Resort General manager Mike Morin says 15 people were evacuated from the lift after the accident, none of whom sustained injuries.

Morin says an empty chair started swinging and then hit a tower, causing the line to go off the track, and  other chairs to fall.

He says the accident involved three men and a woman aged 18 to 35. Three of them were employees of the ski resort. One was a guest. 

Morin says there has never been an incident like this at Crystal Mountain, which has been operating since 1965.

The B.C. Safety Authority is investigating the cause of the accident. 

Crystal Mountain has suspended ski operations pending the investigation.