One post mentioned something about rescue workers in the basement. I would assume that if anything broke through the floor into the basement, it would have been the main (heaviest) part of the helicopter, so rather than a 7-8 foot drop, it could easily have been at least double that.
Further - something could have entered the cockpit - or, if they survived the initial "landing" relatively unscathed, they might have unbuckled and been starting to get out when it dropped.