Cities Murders and non-fatal shootings have been soaring in cities across the United States. One reason is a phenomenon that police refer to as “ping pong murders”—a cycle of retaliatory violence that can spiral out of control. Before that happens, public officials must take quick and decisive action to cut the cycle off. Ping pong murders are a deadly serious phenomenon. Imagine that two gangs in a city occupy territory in adjoining neighborhoods. A member of Gang A kills a member of Gang B over drugs, money, a territorial dispute, an old grudge, or a passing insult. If the murderer is quickly arrested, incarcerated, and prosecuted, the score on the streets will be roughly even. But if the murderer runs free, Gang B will take matters into its own hands by killing a member of Gang A. Hence the ping pong metaphor: they take a shot, we take a shot, they take a shot, we take a shot.