A buildup of ice is being blamed for the partial collapse of a gondola tower on Blackcomb Mountain in Whistler, B.C., that left dozens of passengers stranded in subzero temperatures.

The tower collapsed around 2:30 p.m. Tuesday, trapping 53 skiers and snowboarders for several hours in unheated cabins on the Excalibur Gondola lift. All were rescued, with 12 suffering minor injuries. One staff member was also cut during the evacuation process and sought medical attention.

The most serious injury was a fractured vertebra, Doug Forseth, senior vice-president of operations for the resort, told reporters at a news conference Wednesday.

Most of the injured had bumps and bruises.

Ice-jacking

He said the tower failure occurred when water seeped into a splice on a section of tower four on the lift. Water flowed into the tower, then froze, rupturing the splice as it expanded.

"Water had seeped into the tower which had turned to ice with the recent extreme cold temperatures," the statement said.

It's "an extremely unusual situation referred to as `ice-jacking,"' he said.

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 for those, where it's been damaged," Forseth said.

A precarious situation

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 several people.

One hung over Fitzsimmons Creek as emergency officials worked to stabilize the tower before they could attempt to evacuate trapped passengers.

A team of 20 lift maintenance staff conducted a preliminary inspection overnight of all similar tower structures to make sure that no similar issues exist.

The British Columbia Safety Authority (BCSA) completed its secondary inspection of mountain lifts Wednesday afternoon and has given approval for the resort to continue regular lift operations, with the exception of the Excalibur, which will remain closed until further notice.

"There is no justification at this time that other installations operating at Whistler Blackcomb have been effected by a similar failure," said Greg Paddon, safety manager from the BC Safety Authority.

An isolated incident

Forseth said the safety authority called what happened an "isolated incident." He thanked the local fire department, RCMP and ambulance and medical personnel for their response.

"We are extremely thankful that no one was seriously injured in this incident," he said earlier in the statement.

CTV's Reshmi Nair, reporting Wednesday from Whistler, said the tower that collapsed was located about halfway up the mountain.

"None of the cabins on the cable lines actually came off the wires but there was significant slack in it," Nair told CTV's Canada AM on Wednesday.

The three cabins closest to the ground appear to have taken the brunt of the impact.

"Passengers on board the one closest to the ground said it hit the ground pretty violently, the next cabin actually landed on top of a bus shelter and the third cabin was left dangling above a creek," Nair said.

Passenger Cynthia Jennings, who was in a car halfway up the mountain when the pole snapped, said the ordeal was frightening.

"All we saw were other cars swinging sideways and we thought we were going to crash to the ground," she told CTV News by cellphone.

"I thought the whole cable system was going to come down. I couldn't even breathe."

The fire department used a long ladder to reach some of the passengers.

RCMP Cpl. Peter Thiessen said Wednesday that the gondola's safety mechanisms did "react appropriately."

Skiers were still able to access Blackcomb Mountain from the new Peak 2 Peak gondola.

Resort to be used in 2010

Whistler-Blackcomb 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 $52 million 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.

Past problems

The incident on the Excalibur, which was installed in 1994, is not the first ski lift accident at Whistler-Blackcomb, which will host alpine events at the 2010 Winter Games.

In 1995, an accident on Whistler's Quicksilver lift killed two men, and injured nine others.

The high-speed lift was ferrying skiers to the top of the mountain when a chair slipped on a cable and slammed into another, sending four chairs crashing into the 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.

Elsewhere in BC

Jimmy Spencer of Canada West Ski Areas Association said many other ski resorts in B.C. were making additional safety checks in response to Whistler's accident.

"I've personally contacted them all [and] they're checking their gondola and lift systems, particularly the ones that have the same structures. They're satisfying themselves that everything is in hand and in good order," he said.

With reports from CTV British Columbia's Kent Molgat and Reshme Nair and files from The Canadian Press