This Day in History:, Columbine High School Massacre.
April 20th, 1999.
At 11:19 A.M., Dylan Klebold, 18, and Eric Harris, 17, walked into their high school and began opening fire on students and teachers.
Less than 20 minutes later, Klebold and Harris had killed 12 of their classmates, one teacher and had wounded 23 other people.
Less than an hour after they had begun their rampage, the two died by suicide after turning their guns on themselves.
The massacre in the Denver suburb Littleton, CO, shook the nation and made headlines around the world.
It sparked speculation on the teens' motive and intensified debate on the contentious issue of gun control that would continue for decades.
The methodical and planned-out rampage is widely considered a turning point in the history of school shootings in the United States