Perhaps it was a night auto as a result of some mechanical failure and initially a verticalish, level descent. Then the pilot misjudges the height to cushion (not difficult in those conditions) and either uses up all the NR leaving a short fall to the roof with little cyclic control or, pulling hard as the skids hit the roof, actually gets airborne in a bounce and then the second landing (again with little NR or control) is what actually breaks through the roof.