"The mysterious circumstances and subsequent investigations of the hikers' deaths have inspired much speculation. Investigations of the deaths suggest that the hikers tore open their tent from within, departing barefoot in heavy snow; while the corpses show no signs of struggle, two victims had fractured skulls, two had broken ribs, and one was missing her tongue. According to sources, the victims' clothing contained high levels of radiation - though this was likely added at a later date, since no reference is made to it in contemporary documentation and only in later documents. Soviet investigators determined only that "a compelling unknown force" had caused the deaths, barring entry to the area for years thereafter."

http://en.wikipedia.org/wiki/Dyatlov_Pass_incident

http://www.sfgate.com/cgi-bin/article.cgi?f=/g/a/2008/02/27/notes022708.DTL