As tens of thousands more people continue to flee, one community has found a way to defend itself.
At night, San José Guayabal's streets are filled with little boys and girls. Shops now stay open late into the night in and owners don't have to worry about being extorted. The credit goes to Mayor Mauricio Villanova who, with the help of police, pushed gang members off the streets -- and out of town -- through a network of informants who were fed up with the violence.
Villanova earned the trust of people in the town by promising them that he'll get police to help if they hear or see gang activity. If police are too slow, he patrols the town with a pistol by his side.
The town rules are posted high on a billboard and everyone has to follow the "no tolerance" gang policy.
Villanova told CBS News' Omar Villafranca that you need three things to keep gang violence out: control of the territory, the trust of the people and communication with residents.
The mayor also credits some U.S. aid that helped rebuild the town square. That attracts families and -- so far -- keeps gangs out.