The coastal city of Buenaventura is Colombia's most violent city. There, two rival gangs — La Empresa and Los Urabeños, both successors of paramilitary groups — fight for control, with the city's 400,000 residents caught in the middle. According to a recent report by Human Rights Watch, more than 50,000 of Buenaventura's residents have been forced to flee their homes since 2011 out of fear of extortion, death threats, or forced gang recruitment. Adding to the pervasive fear are accounts of mutilated body parts found washed up along nearby shores — discards from the grimly-named "chopping houses," where victims are dismembered alive. VICE News traveled to Buenaventura to meet with security forces, government officials, crime reporters, gang members, and victims, to try to understand why this city on Colombia's Pacific coast has became so violent, and what's being done about it.