Wiktionary
vb. (context transitive English) To kill by means of a firearm, especially deliberately and in a brutal manner.
WordNet
v. strike down or shoot down
Usage examples of "gun down".
Lieutenant Griggs and the other troopers in Griggs' unit detached from the regiment as an escort for the Princess in her trip were heavily armed, scowling as ferociously as such well-trained and disciplined soldiers ever did, and making absolutely clear with their body language alone that they would instantly gun down any paparazzi who managed to break through the police line.
He put the gun down exactly as he had found it, got back to the door, listened, and then was out and across the corridor and into his own room.
I put the gun down on the desk and stand up, moving toward her so I can stop her from throwing anything else.
When the rider did not appear within a minute he set the gun down and spent a moment removing the cartridges from his gun belt and putting them in his right-hand coat pocket where they could be more easily reached.
From their perch at the edge of Betty Gap they could clearly see the SheVa gun down in the holler, apparently wedged into a ravine.
He'd gotten out of the ventilator shaft a moment before the man emptied his machine gun down it.
I'm going to tell my men to kill your aids and you if you don't lay that gun down.
You don't gun down babies in the dead of night and then run like dogs.