I don't know anything about the circumstances of the person killed by a bullet fired into the air some 3 km away, but in this country I think the coroner would have to return a verdict of accidental death.

I don't think he could say the man was unlawfully killed because there was no intention to kill, nor was it reasonably foreseeable that someone would be killed. I don't even think you could say that the shooter fired recklessly, without caring whether or not someone would be killed, because it would not be within anyone's reasonable contemplation that there could be someone standing precisely where the bullet would land, so far away.