a feud in which members of the opposing parties murder each other
"After years of political infighting, the two warring families finally declared an open vendetta that escalated into a brutal cycle of retaliatory killings."
A bitter, destructive feud, normally between two families, clans, or factions, in which each injury or slaying is revenged: a blood feud.
"The ancient vendetta between the two rival clans has persisted for generations, with every death met by immediate revenge."