This paper studies the effects of legislation in Brazil that banned the right- to-carry guns and provided for a voter referendum regarding whether to ban the sale of all firearms. Using a regression discontinuity design, I find that gun-related homicides decreased by 12.2 percent, with the reduction especially pronounced in high-crime areas and among black males. There is no evidence of substitution effect as non-gun-related homicides were not affected. Analysis of the subsequent voter referendum, which was defeated by a wide margin, shows stronger support for the complete weapons ban in the areas more affected by gun violence.