Deus Ex Machinegun

A scene in films, books, or television in which several antagonists square off in an armed shootout, and in the process of killing one another, conveniently eliminate multiple threats to the protagonist.

Will Smith and Gene Hackman get away in Enemy of the State thanks to a classic deus ex machinegun where the mafia, the CIA, and the local police all kill one another, while it's a deus ex machinegun between rival drug factions that begins the narrative in No Country For Old Men.