It seems like the leading theories fall into one category or the other:
ACT OF NATURE: The group was carelessly camped in space wide open to the elements. It was pitch black, snow swirling, wind blowing, 20 to 30 degrees below zero. For whatever reason, they believed an avalanche, snow slab avalanche or a hurricane was happening. No time to put on shoes or coats, just cut the tent open and get out. They walk single file holding on to the person in front because the wind was howling, or in the dark they didn't want to get separated from each other. The harsh, forbidding environment seems to lend credence to such theories.
ACT OF MAN: A missile explodes releasing toxic nitric acid. A person in the group has secret information to give Russian operatives of the CIA, and the group is murdered by the KGB. The group is tragically caught in the middle of a Soviet military exercise. Theories such as this or others like them are certainly believable. But somehow, some sort of documentation or eye-witness accounts by several people are needed for such explanations to be accepted as the truth. Otherwise, just like the act-of-nature theories, these theories will be speculative.