The Dyalov Pass mysterie

The Dyatlov Pass incident was an event that resulted in the deaths of nine hikers in the northern Ural Mountains on the night of February 2, 1959.
The bodies showed no signs of struggle, such as contusions, two victims had fractured skulls and broken ribs. Soviet autorities determined that an "unknown compelling force" caused the deaths.

Due to the lack of evidences, several theories exist: some involving a possible avalanche, a military accident, or a hostile encounter with extraterrestrial life.