A Continental Airlines jet skidded off a runway and flipped on its back during a takeoff attempt from Denver's Stapleton International Airport during a snowstorm yesterday, killing 26 of the 82 aboard and trapping others inside the broken fuselage for five hours.

The twin-engine DC9 was carrying 77 passengers and five crew members on Flight 1713 to Boise; the accident occurred about 2:13 p.m. local time (4:13 EST), a Continental spokesman said. The flight had originated in Des Moines.

"I couldn't see through the snow," said Norm Avery, a Denver airport spokesman, when asked to describe the crash scene. The plane apparently skidded a quarter-mile before stopping between the airport's two parallel north-south runways.

Sources close to the scene said the jet broke into three pieces and came to rest facing the airport, after making a 180-degree turn during its quarter-mile slide. The jet's fuselage broke apart just in front of the tail section. The left wing broke off, trapping some passengers underneath for up to five hours.

A passenger, Libby Smoot, of Ketchum, Idaho, said she felt the plane "tip to the right, then tip to the left before turning over and landing on its roof."

The plane's pilot, Frank Zvonek, 43, and first officer Lee Bruecher, 26, were killed in the crash, as was flight service officer Diana Mechling, 33, said Continental Vice President Bruce Hicks. He said flight attendants Chris Metts, 27, and Kelly Engelhardt, 35, survived.

The passenger list included eight student Future Farmers of America from Melba, Idaho, and two teachers from Melba High School, United Press International reported. The group had been attending an FFA convention in Kansas City, which ended Saturday. In Boise, relatives said at least four of the students survived the crash.

At least a dozen city fire trucks responded to the accident. But the scene was so confusing and visibility so poor that accident investigators couldn't determine at first whether the plane ever left the ground.

"If it got off, it was not far enough for it to be detected by radar," said Fred Farrar, a spokesman for the Federal Aviation Administration.

The airport's main terminal building and the FAA's air traffic control tower were more than two miles south of the wreckage. Immediately after the accident, witnesses reported seeing a "fireball," but rescuers said there was no evidence that any injuries were caused by fire.

"We had reports of a large fireball from the tower, but visibility is so bad, they couldn't see what happened from the tower," said Denver police Sgt. Ed Connors.

A source close to the investigation said a small fire broke out around the plane's engines after the accident, but there was no immediate evidence of any engine failure. The jet's outside was virtually free from fire damage, which airport officials said helped limit the number of fatalities.

Three hours after the accident, the temperature at the airport had dropped into the mid-20s and rescue workers used auxiliary power units to blow hot air onto the survivors still trapped in the fuselage. Medics administered intravenous fluids to stabilize the more seriously injured while firefighters cut through the jet's aluminum skin to free them.

Richard Boulware, an airport spokesman, said 56 passengers were taken to three hospitals in the Denver area. Their conditions ranged from critical to "walking wounded," according to a nurse at Denver General Hospital.

One survivor, Fred H. Helpenstell of Nampa, Idaho, had to be treated for hypothermia because it took rescuers two hours to cut him from the wreckage.

"We counted 18 dead outside the plane, and there are several dead in the fuselage," Boulware told the Associated Press. He said 21 persons walked away from the crash. He also said visibility was reduced by the snowstorm to an eighth of a mile when the jet slipped off the runway and flipped over.

Police Detective John Wyckoff told United Press International that bodies were scattered around inside the wreckage, which was lying off the runway. "It's a terrible sight at this time . . . just a chaotic scene," he said. "It's a disaster scene; there are many injuries; there are fatalities . . . . It's a mess."

"It's bad, it's real bad," said Karen Lavigni, a switchboard operator at the airport.

A major snowstorm hit Denver yesterday, with winds gusting up to 27 miles per hour and dumping up to 18 inches of snow in outlying areas. At the airport, six inches of snow accumulated during the day. Meteorologists said fog moved into the area yesterday afternoon, further reducing visibility.

Earlier in the day, gusting winds had forced airport officials to close two major east-west runways, but officials from both Continental and United Airlines, the two main carriers operating out of Denver, reported normal operations.

Airport officials said the two north-south runways were open, with very little snow on them, at the time of the accident.

"This was not a bad snow day," Avery said. "It was not one of those days when you wring your hands and say, 'We can't get through the day.' "

After the crash the airport was closed until 8 p.m. local time.

National Transportation Safety Board Chairman Jim Burnett prepared last night to direct an investigation of the accident. Many NTSB staff members were in Detroit yesterday, preparing for a public hearing on the Aug. 16 crash of a Northwest Airlines jet at the Detroit Municipal Airport, which killed 156 persons.

Several NTSB investigators were dispatched to Denver from Detroit. The FAA dispatched two investigators from headquarters here and several from its Denver office, a spokesman said.

The plane's black box, containing cockpit voice and data recorders, was recovered and being held for the investigators, Avery said.

Continental's last fatal crash occurred in 1978, when two passengers were killed trying to escape from a DC10 after the pilot aborted a takeoff at the Los Angeles International Airport.

Staff writers Sari Horowitz and Veronica Jennings contributed to this report.