How are they not? They’re definitely armed, so only the “gang” part is questionable. Wikipedia says:

“A gang is a group or society of associates, friends, or members of a family with a defined leadership and internal organization that identifies with or claims control over territory in a community and engages, either individually or collectively, in illegal, and possibly violent, behavior, with such behavior often constituting a form of organized crime.”

I’d say that fits some law enforcement pretty well.