The saving grace for me is by the time I get out my good rifle, load it and get outside, any aircraft should be long gone. However, were they within 100 yards, that might change the scenario a bit.
The fact is, if one takes out the engine(s), (which it would be very difficult were there two engines), a helicopter CAN auto-rotate to the ground. Given a decent pilot, there should be NO deaths.
I probably would be on the phone with the Sheriff until I received some sort of hostile intent.