TOKYO - Investigators pored over a mountain on Tuesday after an avalanche tore through a group of high school students and teachers, killing eight, amid questions about why avalanche warnings were ignored and whether they had proper equipment.

The avalanche in central Japan on Monday, which struck along 50 meters of a steep slope just above a ski area, killed seven students and an instructor who were part of a 48-person group taking part in winter climbing training.

Thirty-eight people were injured, two of them critically.

Survivors said they were training in a wooded area in Nasu, a town in Tochigi prefecture, when suddenly there were shouts of "Avalanche, get out of here!" and voices yelling to take cover.

"A second later the snow was there and I was buried up to my chest," said one 16-year-old student. "My face was free, so I managed to get myself out. It was scary."

The students who died, all aged 16 and 17, were from a local high school known for its prowess in competitive mountain climbing.

The father of Kosuke Sato, 16, one of those who died, displayed the torn windbreaker his son had worn. "I still can't believe it," he said.

The group changed its original plan to climb a nearby mountain due to heavy snow and strong winds, switching instead to practicing walking in deep snow on a steep slope, media said.

"Spring is much more dangerous in terms of avalanches than winter," said mountaineer Ken Noguchi, himself the survivor of several avalanches.

Others blamed temperature fluctuations and deep, fresh snowfall on top of older snow.

A police spokesman said investigations, which included the use of drones, were focused on whether or not there had been errors of judgment, in particular by the Tochigi High School Athletics Federation, which sponsored the training.