WHISTLER, B.C. - Officials at the ski resort in Whistler, B.C., say an unexpected and undetected build up of ice brought down a ski lift tower, stranding dozens of terrified passengers for hours in disabled gondolas hanging precariously from downed lift lines.

Twelve people were slightly injured among the 53 skiers and snowboarders trapped in the unheated cabins after the tower on the Excalibur gondola buckled Tuesday afternoon. One staff member was also cut during the evacuation process and sought medical attention.

Doug Forseth, senior vice-president of operations for the resort, said the most serious injury was a fractured vertebrae. Most of the injured had bumps and bruises, he told reporters at a news conference Wednesday.

Forseth said the tower failure occurred when water seeped into a splice on a section of tower four on the lift. The water froze as temperatures plummeted, rupturing the splice as it expanded into ice.

Resort officials called it "an extremely unusual situation referred to as `ice-jacking."'

Forseth said he has confidence in the safety systems in place at the resort but acknowledged that the incident may leave some people wondering.

"We're going to work very hard to restore the confidence where it's been damaged," Forseth said.

Sue Makinson-Sanders said she thought she was going to die as the gondola she was riding slammed into a house, bounced of some trees and then hung precariously over a creek for hours.

"Our gondola started to clip the tree tops and the next few minutes were the most terrifying of my life," she said. "Once the gondola stopped, we all sat very still because we thought we were going to plummet into the river."

Yet the 50-year-old British tourist said she will finish her planned two-week vacation and even return to the slopes on Thursday.

"I am a little stiff and sore... but I plan on going back up Whistler Mountain because if I don't face my fears, I will never ski again," she said.

Resort officials said all the gondola cabins remained on the line but a number of them dropped about nine metres as the line sagged after the tower buckled. Two of them bounced off the ground, injuring passengers.

Forseth said emergency officials had to stabilize the tower before they could attempt an evacuation.

The Excalibur gondola was built in 1995 and went through a safety inspection in October.

"At the time, we were not able to tell there was water in the tower," Forseth said. "We don't think we were negligent or missing anything."

A team of 20 lift maintenance staff spent the night inspecting the resort's lifts for similar problems.

The British Columbia Safety Authority, along with resort staff, were inspecting the lifts at the resort Wednesday.

All but the Excalibur were expected to be in operation by the end of the day.

Forseth thanked the local fire department, RCMP and ambulance and medical personnel for their response.

"We're very thankful that this accident was no more serious than it was," he said.

The resort will play host to the alpine events at the 2010 Winter Games. All of the events will take place on Whistler Mountain, not Blackcomb where the accident occurred.

Many feared the collapse had occurred on the new Peak-to-Peak lift, connecting the peak of Whistler Mountain to the peak of Blackcomb Mountain. It's the highest in the world at 436 metres above the ground.

The incident on the Excalibur is not the first ski lift accident at the resort.

A Dec. 23, 1995, accident on the Quicksilver ski lift killed two men and injured nine other people.

The high-speed lift was ferrying skiers to the top of a run when one chair slipped on a cable and slammed into another, setting off a cascade that sent four chairs crashing into the bush and rocks three storeys below.

A coroner's report said the accident was a result of systemic failure, noting problems with the lift system's grip mechanisms should have been detected in advance.

In January 2006, two empty gondola cars at the Sunshine Village ski resort near Banff, Alta., plummeted to the ground after being dislodged from their cables by high winds. No one was injured.