NOW With Alex Wagner 09/17/13

Cullen: Mass shooters always seeking attention

Monday’s shooting at the Navy Yard in Washington, D.C. marks the fifth mass shooting since Newtown. MSNBC.com’s Richard Wolffe, Dave Cullen, author of “Columbine,” Heather McGhee from Demos and Mark Glaze from Mayors Against Illegal Guns join Alex ... more Duration: {{video.duration.momentjs}}