I will jump in with my spin on objecting to "gone awry."
The words "gone awry" seem to imply that success was anticipated by the robbers.
The robber(s) may have anticipated success, but the bad act just started a chain reaction of which one link is the dead victim and the next link is affront to law-abiding citizens that the shooter is on the loose. The final links on this chain will be the capture, trial, and punishment of the shooter.
Vigilantes and bounty hunters had their rightful place in days past.
I will jump in with my spin The phrase "gone awry" seems to connote at least some degree of either innocence or naivete. "The best laid plans of mice and men, gang aft agley!" so it fails on connotation. Furthermore if killing is a foreseeable and even expected eventuality in armed robbery then the phrase "gone awry" fails on denotation as well.
Thanks for your thoughts.