In American action movies, to "get" someone is to successfully kill or make unable to fight an enemy in a gunfight.
This use was a feature of idiomatic speech in the U.S. Army long before ever seeing the movie screen.
Example: In "Cop Out," the goofy African-American sidekick "Paul" (played by Tracy Morgan) to Bruce Willis' character "Jimmy," successfully shoots "a bad guy" in a gunfight within the corridor directly behind the front door of a house owned by a notorious drug dealer.
"Jimmy" (Bruce Willis) asks, "Did you get him?"
"Paul" (Tracy Morgan) replies, "His head ain't on his body no more, does that count?" [Rough paraphrasing. I only saw the movie because a family member rented it.]
This means, the bad guy's head had been "taken off" by the gunshot so yes, that was probably a fatal shot. (Probably?)