Who knows...
Time has passed and the story's been told many times. Reports are missing and people want to fill in the blanks.
It wasn't ufos or Bigfoot. My first thought it was one of them.
I read a couple of sources and the time frame isn't clear. And some say they scattered and another said they all grouped at the tree and some tried to return to the tent. If they were hiding, why build a fire 1600 feet from the tent? If they were found one month or two months after the event, could the weight of "12 feet" of snow crush decomposing bodies.