JHR & Auscan I agree.
A tragedy for all concerned. My condolences to the families of the deceased, and the injured and their families; my heartfelt sympathies to the pilot and his/her family.
Skiing is regarded, at least by insurers, as a dangerous sport, but what odds of being on a cable car when the line gets hit with a block of concrete released from a thousand feet; as Recuperator intimated it is hardly believable.
Even with the ballistic coefficient of a block of concrete the aircraft would not have even reached the line when the release occurred.