"Trigger Points": Author Mark Follman on How the U.S. Can Prevent More Mass Shootings

As the United States reels from an epidemic of mass shootings in schools, trains and other public places, we speak with Mark Follman, national affairs editor at Mother Jones, where he covers gun violence. Follman says mass shootings are typically planned over a period of time and follow a robust trail of behavioral warning signs" that offer opportunities in community-based violence prevention to stop the crime before it happens. His new piece, Horror on the NYC Subway - and How to Prevent the Next Attack," draws on insights from his new book, Trigger Points: Inside the Mission to Stop Mass Shootings in America."