How survivors of Columbine are coping, 20 years later

It has been nearly 20 years since the first mass school shooting in the U.S. -- the shocking tragedy at Columbine High School in Littleton, Colorado, on April 20, 1999. As a “credible” threat closed Columbine and hundreds of other Denver schools Wednesday, John Ferrugia of Rocky Mountain PBS shares part of an upcoming documentary featuring survivors of the massacre in their own words.