An absolute “hh rule”:
Vigilantism rises because of the unwillingness or inability of law enforcement to do their jobs.....
hh
This was not an act of vigilantism. That would occur if a group of armed men went to the house of gang members to seek retribution for a crime committed by members of the gang.
This was a fortuitous act of self defense, stopping a threatening murderer in progress of shooting innocent victims.
I trust he has been given a gun to protect his home and family from the vigilantism of gang members.