The already precarious city of Karachi, Pakistan, has seen a bloody three days, with at least 39 people killed. Violence has swept the city as rival groups battle for turf. Though largely political in nature, the violence fits into a pattern of mafia control and extortion rackets that hold sway in the port city. Residents say they’re afraid to leave their houses and are running low on food and basic provisions. But it’s dangerous to leave home, with stray bullets striking a 5-year-old in one case and gunmen shooting five minibus passengers in another. The violence also poses a threat to the nation’s economy, as Karachi is a key economic center.