The Ski Granby Ranch chairlift from which a Texas mom and her two young daughters fell late last month had problems with its electrical drive-control system that contributed to a “rare dynamic event” at the time of the accident, a preliminary state report released Monday shows.

The chair carrying 40-year-old Kelly Huber and her children struck a lift tower about a third of the way up the mountain before the three fell roughly 25 feet onto hard-packed snow. Huber was killed. Her daughters were injured.

“The circumstances indicated that environmental factors, weather and the occupants of (the chair) did not contribute to the cause of the incident,” the Colorado Passenger Tramway Safety Board report says, adding: “The facts of the incident show that, on Dec. 29, 2016, an unreasonable hazard existed in the continued operation of the lift.”

The report, released after more than a week of investigation by the board, police and the resort, provides the first official details of what led up to the fall. Granby police say witnesses reported Huber and her daughters were not involved in any horseplay before they came off the chair, nor did witnesses report any kind of intentional or user-caused accidental fall.

The Colorado Passenger Tramway Safety Board did not respond to requests for comment on the report, and said in a statement, “This is an ongoing investigation and there will be no further comment until the investigation is complete.” A final report will be released later.

Huber was pronounced dead at about 10:45 a.m. Dec. 29 at Middle Park Medical Center in Granby, where she was taken after falling about an hour earlier.

The Grand County Coroner ruled Huber died from blunt force trauma to her torso and a traumatic rupture of her aorta. The four-person, high-speed Quickdraw Express lift, built by Grand Junction-based Leitner-Poma in 1999, has been closed since the incident but is scheduled to reopen Tuesday.

The Colorado Passenger Tramway Safety Board has since found that the lift’s diesel prime mover is capable of safely operating.

As part of an agreement to reopen the lift, Ski Granby Ranch will run the Quickdraw Express below its rated speed capacity of 900 feet per minute, increasing the speed to 800 feet per minute over a five-day period.

“Operator will increase surveillance and inspection of the lift,” the board’s report, an operating agreement with Ski Granby Ranch, said. It added: “Upon finding any irregular conditions or operation of the lift, Operator shall immediately and safely slow and shut down the lift, evacuate all passengers from the lift, and immediately report such irregular conditions or operations.”

In a statement Monday night, Ski Granby Ranch CEO Melissa Cipriani said the Quickdraw Express lift was load-tested Dec. 5, before the resort’s ski season began Dec. 16. She said the Huber family’s fall was the first incident of its kind in the resort’s 22 years of operation and that the lift has been operating safely since its installation.

“Granby Ranch strictly adheres to all policies, procedures and regulations for safe lift operation. … Lift protocols for operation of the lift were determined by an outside engineering expert at the time of certification,” Cipriani wrote. “Granby Ranch has followed all prescribed protocols in operating the lift. There is no indication at this stage of the preliminary investigation that the original lift installation contributed to the incident.”

In a Ski Granby Ranch Facebook post made about the time the state report was released said the resort has been working “tirelessly” with investigators to probe the Huber family’s fall.

“Granby Ranch would, again, like to extend its condolences to the family of our guest who lost her life, and her family members who were injured in this tragic event,” the post said. “Granby Ranch places the highest value on the safety of our guests and the safe operation of all lifts and equipment at the resort. We would like to thank all of our guests, homeowners and team members for their supportive words and thoughts during this very difficult time.”

Huber’s death was the first resulting from a fall from a Colorado chairlift since 2002. Of the more than 250 chairlift falls since then, most have been attributed to skier error, according to state data.

According to an October report by the National Ski Areas Association, the last death on a chairlift attributed to a malfunction was in 1993. As of the 2015-16 ski season, the annual fatality rate per 100 million miles traveled on ski lifts was 0.14.

In 1976, two cars from Vail’s 7-year-old gondola – each carrying six skiers – plummeted 125 feet, killing four people in one of the most deadly lift incidents in the United States. In 1985, a bullwheel at Keystone Resort failed, sending waves down the line that threw 60 people off the Teller Lift, two of whom later died from their injuries.

The ski industry stresses that chairlift falls — especially fatal ones — are extremely rare considering the millions of rides taken each year.

Huber’s 9-year-old daughter was taken to Middle Park before being flown by Flight for Life to Children’s Hospital Colorado. Children’s Hospital said family members declined to allow information on her condition to be released.

Her other daughter, who is 12, was treated at Middle Park and released.

Huber, who lived in San Antonio, was vacationing in Colorado with her daughters and other family members at the time of the fall, authorities say.