Now this guy is a diffinate Darwin Award winner right here.
If you go in to a gun store and rent a gun. Then proceed to load that gun standing at the counter. The clerk has his hand on his side arm prepared to kill you.
First rule on the gun range (I assume he was renting the gun to use on the gun range) is you do not load the gun until you are in your booth ready to shoot.
If you are loading your gun at the sales counter I will assume you intend to rob the store or you are a novice and a fool. Either way I will be ready to shoot you. I wont loose my life to a thief or a fool.
The dead perp used the range first then came in and shot the clerk who returned fire.