Much will depend on the nature of the strike.It's theoretically possible for the main rotor blades to impact something solid like a tree and survive.This would depend on the thickness of the tree and how much overlap occurred.In a best case scenario with say,the end 50cm striking high up on a thin branch it's quite likely that damage would not be critical.At the opposite end of the scale a strike half way along the blade against a thick branch then I think a catastrophic failure and immediate crash would ensue.
Somewhere between the most likely outcome would be critical damage but not enough to prevent some degree of control being retained.The impact would almost certainly knock out bearings in the gearbox and cause malalignement of the rotors and potential loss of control.If this has happened they were probably unlucky because a slightly smaller impact would have permitted sufficient control to be retained to allow an emergency landing.