Experts analyze the underlying causes of mass gun violence

How do we explain and stop mass shootings like those in El Paso and Dayton? Some Americans point to guns, saying they're too common and easy to obtain, while others emphasize the mental and emotional conditions that could drive perpetrators to inflict such horror. Amna Nawaz talks to Dr. Garen Wintemute of UC Davis Medical Center and Duke University's Jeffrey Swanson for analysis of both theories.