There's an epidemic of PTSD in American cities, and it has nothing to do with the wars being fought abroad. Homegrown violence and a sense of impunity in America's urban war zones are leaving thousands of teenagers with severe psychological trauma that stunts their emotional and cognitive development.VICE News travels to the front line of this epidemic in Los Angeles to speak to the kids who are suffering, and the adults trying to save them from being destined for the fringes of society.