There is nothing wrong with dropping to the ground if you know that the gendarmes have arrived. The point is self defense until such time as the uniformed personnel take over defensive activities. Or offensive, perhaps. If you hear "drop your gun" types of commands that's a good time to comply and do that.

I think that when it comes to armed civilians your one goal is defense of self and family or whomever you are with and whomever is around you. If your shots cause offenders to move away you DO NOT chase them. That's not your job. Stay out of the way of the good guys who arrived.