The eager climbers had trekked less than halfway up the cold, snowy south slope of this deceptively gentle mountain when the first signs of trouble appeared.

With a brutal wind in their faces and wet snow clinging to their legs, five members of the highly competitive wilderness class from Oregon Episcopal School in Portland announced that they could go no farther. With considerable disappointment, one of the five teen-agers said later, they left 10 schoolmates and three adults to push for the summit.

The five disappointed students turned out to be the lucky ones.

The remaining climbers hiked into a tortuous ordeal that left three frozen on the mountainside and eight others, six found too cold to be revived, jammed for three days and nights in a makeshift snow cave about the size of a compact car. Two climbers staggered off the mountain under their own power, and two others remain hospitalized, one with both legs amputated below the knee, after being airlifted to safety following an intense three-day search.

The excursion that began before dawn that Monday has prompted extensive questioning here about what went wrong. Why didn't the hikers -- warmly dressed in wool sweaters, long-johns and waterproof outer garments and led by two experienced climbers -- turn back sooner? Why didn't they leave a tall marker in the snow when they dug their cave? Should they have been better prepared for bad weather on this glacial peak that, in good weather, lures about 10,000 climbers each year?

The less ambitious set out in mid-morning for a brisk walk along the gentle rise near the base. Those determined to reach the 11,245-foot summit come hell or high winds start their hike just after midnight, aiming to reach the summit when the sun is high, take in the view of the Cascade range and scramble down before the harsh afternoon winds begin to build and ice and rock begin to fall from cliffs.

The hikers who died here last week were among the latter.

They were mainly 10th-graders taking part in the "Sophomore Ascent," an important annual ritual at the school, an exclusive academy on a lush campus beside the sixth fairway of the Portland Golf Club. Its students tend to be high achievers -- National Merit finalists and debate champions expected to go to prestigious colleges.

The school, like several others in environmentally conscious Portland, runs a four-year outdoor program designed to give the students a sense of accomplishment. In a letter of recommendation last fall for one of the students on last week's trip, the school noted that the student "had an intense drive to complete well whatever she begins -- particularly in her mountain climbing."

To make sure they would complete the ascent of Mount Hood well, the 15 students and three adults set off at 2:30 a.m. May 12 after a midnight bus trip to Timberline Lodge about 5,000 feet below the summit. For days, the weather had been unstable and unpredictable, and the forecast was for freezing rain or snow and falling temperatures.

Clackamas County Sheriff's Lt. Don Vicars said the students from Oregon Episcopal were the only climbers on the mountain that day, not unusual for a weekday. The cold wind and cloudy sky with which they began gave way to kinder conditions after dawn, then returned as the afternoon wore on and the temperature fell.

The party pressed on but was short of the summit when its professional guide, Ralph Summers, and its faculty leader, the Rev. Thomas Goman, told the exhausted students that they must turn back. To the pain of cold and exhaustion thus was added the disappointment of failure. They knew now that they would not make it to the top. They did not know that most would not make it to the bottom.

At midafternoon, the 13 climbers suddenly were enveloped in a white haze of snow and cloud so thick they could not see one another or tell uphill from downhill. A rescue worker later said the sensation is "like walking inside a ping-pong ball."

In decent weather, Summers said later, the hikers could have made it back to the lodge in two hours or so. But after the group had struggled for about an hour against winds up to 50 mph, one student showed signs of hypothermia, extreme exposure to the cold. He was disoriented, lethargic, too tired to go on.

Somebody had a sleeping bag in a backpack, and the youth was wrapped in it while the others waited an hour in the driving snow for him to revive. Finally, Goman picked him up, and they set out again. With the sun beginning to sink, word was relayed from the lodge to the students' parents that they were late. But the weather at the lodge and in Portland was mild, if gray, and there was no apparent alarm.

By 5:30 p.m., after 15 hours of trudging, Goman and Summers decided that the climbers would have to dig a cave in the drifting snow and huddle there for the night, hoping for a break in the weather. Two hours of digging produced an opening barely large enough for the hikers to pack themselves in, one atop the other, leaving their gear outside. There they spent a painful, mostly sleepless night, Summers said later.

The students had practiced for this. Goman, who had climbed Mount Hood 18 times, headed the school's advanced climbing team of juniors and seniors. Each year, a sophomore was assigned to a senior for training in climbs, and cave-digging, on the mountain's lower slopes. The advanced team had climbed Mount Hood in January, when temperatures were colder, the snow drier, the footing firmer.

U.S. Forest Service officials said this week that Summers was not registered, as required, as a Mount Hood guide. Outward Bound officials say he is an 11-year mountain instructor in the Northwest, trained more rigorously than government standards require. They report that he does not have a telephone, and he has not been reached for comment. School officials and families are politely shielding the climbers who turned back and those who survived from outsiders' questions.

With the mountain dark and the climbers nowhere in sight, Charles Reynolds, the bus driver who had brought the climbers to Timberline, called the Clackamas County sheriff's office at 9:30 p.m. Desk officer Damien Coates took the call -- routine, so far, for authorities so close to a popular mountain where climbers often break ankles or tumble into crevasses.

Coates alerted the usual groups: the Forest Service, mountaineering clubs that regularly participate in searches and rescues and the Air Force Reserve's 304th Aerospace Rescue and Recovery Squadron. When Summers and one of the students arrived at the lodge Tuesday morning, a large contingent of rescuers was standing by.

Summers and senior Molly Schula, at 17 the oldest student climber, had set out at 5:30 a.m. Tuesday, straying off course in the storm. Had they walked straight down, they would have been an hour or two from Timberline. Instead they moved laterally, emerging at Mount Hood Meadows ski slope to the east where they called the lodge and waited for rescuers to drive them down the slope and back up to Timberline.

The other climbers remained stacked in their cave, the heat of their bodies melting the snow beneath them so that those on the bottom of the pile lay in a puddle of frigid water. Summers told rescuers that when he and Schula left the six teen-agers, Goman and dean of students Marion Horwell, they were cold, tired and scared, but healthy.

High winds prevented close-in use of helicopters. The sheriff's office, fearing avalanches, rejected volunteers' offers to rappel into the area where the climbers were believed to be. Men on foot inched their way up and across the mountain, but systematic rescue efforts were stymied.

But the rescuers' morale was high. Master Sgt. Richard Harder of the 304th told reporters at the lodge -- most of them local -- that if the weather cleared Wednesday, they would find the students by 7 a.m. and throw "a hell of a party by 7:30."

Wednesday dawned bright and sunny, helicopters went aloft, and three bodies were spotted in the snow at about 8,300 feet. Whether because they were cramped or confused from cold, the three had left the cave. Hypothermia experts say that when body temperature drops below 86 degrees, shivering ceases and a pleasant sensation of warmth sets in. At this stage, disoriented victims may do irrational things, such as undressing or lying down in the snow.

The bodies of Erin O'Leary, Erik L. Sandvik and Alison Litzenberger, all 15, were flown by helicopter to Emanuel Hospital in Portland, where doctors began to thaw their bodies from inside out by connecting their circulatory systems to bypass machines and returning their warmed blood to their bodies. Erik's heart beat for four hours. Neither Erin, who was running for student body president against another climber on the trip, nor Alison ever responded.

Summers had taken an azimuth reading before leaving the cave, guessing at the relative locations of the cave and the lodge on his map of the mountain and at the angle between. Rescuers set out from the lodge at that angle, but Summers had had no altimeter to pinpoint the cave's height. There was no sign of the cave where the first three bodies were found, and rescuers did not know whether or how far they had wandered from the cave. The landscape had been so changed by blowing snow that Summers could help rescuers only by instinct.

Through Wednesday night and into Thursday afternoon, mountaineers pushed 12-foot aluminum probes into the snow, working down the mountain in teams beginning at 10,000 feet. German shepherds sniffed the snow for human scents and listened for the heartbeats they are specially trained to hear. A Bell JetRanger helicopter hovered a few feet above the snow, probing with infrared scanners that detect small temperature changes.

By Thursday afternoon, hope faltered but was not abandoned. "The chances of finding them, to be honest, are just about impossible," an exhausted dog-handler said. But Clackamas County deputy Russ Williams, his eyes a little glazed, told reporters, "We're hoping to find a cave with eight people -- real glad to see us."

"Never have I seen one so difficult to get a finger on," said Hood River deputy Bill Bryan, a leather-faced 40-year veteran of Mount Hood rescues.

Many family members who had gathered at the lodge returned to Portland to wait. Those who stayed turned sullen or talked optimistically or simply stared at the mountain. "That mountain's so close, I feel I can reach out and touch her," said Donald Penater, Horwell's brother.

At 5 p.m., clouds moved in from the west, and a cautious command station radioed the 17 exhausted rescuers still on the mountain that they had better get ready to come down.

"I'd be lynched if I tried to get them down now," a team leader radioed back.

"We're looking in a promising area," another voice said.

The base station did not know that Summers, aloft in a helicopter, had had a hunch. "This looks familiar," companions quoted him later. "It's gotta be the place."

"It sort of felt right," he told reporters later.

Master Sgt. Charlie Ek moved ahead of the probers to look for hidden crevasses. Secured by a rope held by a fellow rescuer, he leaned over cliffs to probe innocent-looking snow that might hide deep holes. At about 5:20 p.m., Ek's pole hit something soft: a backpack just beneath the surface.

As searchers converged on the area, other packs and equipment were uncovered. Then came the feeling that everyone had hoped for with every push for three days: Ek's probe broke through to open space. Beneath four feet of new snow, they dug into the snow cave, only five feet from where one of the three bodies was found.

"There was noise," Ek said. "They were moaning and groaning. That's all we need to hear -- life."

There are several versions of what Ek said when he emerged from the cave, but according to Harder, it took a moment for everyone to believe him.

"He said, 'They're talking to us,' " Harder said. "I wanted to beat him up for joking about it."

Harder radioed, "We have patients."

Parents and friends at the lodge hugged and broke into sobs as Harder radioed, "The patients are conscious. They're not alert, but they're conscious."

Gradually, it became clear that the families' elation was premature. For what seemed a long time, Harder mentioned only two patients, ignoring questions about the others.

At one point, as the base asked again for the number of patients and their conditions, Schula looked up at a reporter listening on a small scanner and said, "He won't answer that."

Unable to get needles of heart-stimulating lidocaine into the climber's collapsed veins, unwilling to risk having thermometers snapped off by their stiff jaws and unable to get an answer to his demands for advice on whether to move them, Harder radioed, "Forget it. We're moving the patients on my medical expertise. Two minutes -- you can set your watch."

The base answered quickly, "The doctor says get them out of there."

More than an hour later, when all eight climbers had been moved to the helicopter staging area nearby, Harder reluctantly radioed, "We have two alive for sure . . . . I don't think I have anyone else conscious and breathing."

Helicopters raced the eight frozen hikers to Portland hospitals. Some were pronounced dead within minutes of arrival. Others were kept alive -- in a clinical sense, at least -- for several hours. Brinton Clark, found in the middle of the pile, and Giles Lewis Thompson, a solidly built athlete found on top of Clark, survived.

Dr. Robert Long, who treated Thompson at Providence Medical Center, said Thompson owed his survival to his strength and rubber climbing leggings that, unlike wool, shed wet snow. Nonetheless, the dead tissue in his legs eventually threatened his life, and they were amputated below the knee.

Long said that when Thompson came around, hours after his midnight flight to the hospital, he told his doctors and family that the last thing he remembered was being in the cave, expecting to die.