Culling The Herd... 

That's what it is called. Definition here.  Boom, boom, out go the lights.

On July 12, a man knocking on doors at San Antonio's Grand Hyatt while trying to find "someone to kill" came across an armed guest who shot him dead.

According to MySanAntonio.com, 34-year-old Moises Torres "started breaking lights in the hallway" on the sixth floor and then knocked on a guest's door around 1 p.m. When the guest opened the door, Torres said he was "looking for someone to kill."
The guest slammed the door, and Torres knocked on another one. The guest inside the second room was 43-year-old concealed carry license holder John Neal, who retrieved a gun and "waited until he thought Torres had left before opening the door."
But when Neal opened the door, Torres "charged at Neal and another woman." So Neal "drew a pistol and fired one shot at Torres, stopping him in the doorway."
Torres died at the scene.