It has been 13 years since the terrifying mass shooting at a Colorado high school.
On April 20, 1999, students Dylan Klebold and Eric Harris shot and killed 13 people, and wounded 23 others at Columbine High School, near Denver.
The teens then took their own lives before they could be captured by police.
Among the victims were 12 students and teacher Dave Sanders, who died while directing students to safety.
A memorial now stands not far from the high school in Littleton, CO.