This Day in History: April 20, 1999

Yearbook photos of Eric Harris (left) and Dylan Klebold (right)

Twenty years ago today, Eric Harris and Dylan Klebold, seniors at Columbine High School in Columbine, Colorado, killed twelve of their classmates and a teacher during one of the most deadly school shootings in the twentieth century before committing suicide. Another twenty-one students were injured.

There had been other school shootings before. The first modern school shooting actually took place in