It seems pretty odd that they should all pile into what is essentially an isolated mountain in an otherwise unobstructed area.
Plenty of possible scenarios and though the tendency is to assume incompetence - plus there have been many cases of multiple helo losses in the aftermath of a single accident, S Georgia and the more recent one in - hell, where was it? Thailand? And, as said above, cumulo granitus encounters aren't restricted to 3rd world AirForces.
Time will tell, but I'm willing to bet the tale will be one you couldn't make up if you tried, and if you did no one would believe it...