What is April 20th famous for?
The Columbine High School massacre was a mass shooting that occurred on April 20, 1999, at Columbine High School in Columbine, Colorado, United States.

An FBI diagram of the library, with locations of fatalities
United States Federal Bureau of Investigation – http://www.cnn.com/SPECIALS/2000/columbine.cd/Pages/Sketch_0088.htm
The shooting was carried out by two senior students, Eric Harris and Dylan Klebold, who killed 12 students and one teacher before taking their own lives.
The massacre is considered one of the deadliest school shootings in U.S. history. And had a profound impact on the country’s psyche. It sparked a national debate on gun control and school safety, and it led to changes in the way schools handle and prevent acts of violence.
The two shooters, Eric Harris and Dylan Klebold, known to be outcasts who had been planning the attack for months. They had amassed an arsenal of weapons and explosives, which they used to carry out their plan. The attack began around 11:19 a.m. when the two students entered the school building and started shooting. They moved from room to room, targeting anyone they came across.

Ophicvs – http://en.wikipedia.org/wiki/File:Hp995carbine2.jpg
The police arrived on the scene within minutes, but the shooting continued for nearly an hour and 20 minutes. In addition to the 13 people killed, 24 others became injured.
Furthermore, the shooting sent shockwaves throughout the country. In addition, prompted a national conversation about gun control and mental health. It also led to changes in school safety procedures. Such as the implementation of lockdown drills and the hiring of school resource officers.
Lastly, the Columbine massacre remains a tragic reminder of the potential for violence in schools and the need for continued efforts to prevent such acts.
What is April 20th famous for?