Within days of the Columbine High School shooting, University of Colorado band students wanted to help and organized a commission for a new piece of music for the high school band. The piece, “American Elegy,” by composer Frank Ticheli, premiered a year after the shooting. Since then it’s been performed over 10,000 times.

Boulder's Mass Shooting Takes Frank DeAngelis Right Back To Columbine

On April 20, 1999 a school shooting in Littleton, Colo., shook the country. Now, 20 years later, Reporters Nate Minor and Andrea Dukakis look at how one shooting changed America and what we've learned since.