School Shootings Since Columbine: By the Numbers

— -- In a Diane Sawyer special edition of “20/20,” she speaks with Sue Klebold, the mother of Columbine killer Dylan Klebold. ABC News examined the impact and lessons from that tragic day that changed the nation. The numbers that follow are a part of a larger conversation about school violence and children in crisis:

50 – The number of mass murders or attempted mass murders at a school since Columbine. (FBI records)

141 – The number of people killed in a mass murder or attempted mass murder at a school since Columbine. (FBI records)

73 – The percentage of school shooters with no prior criminal record, not even an arrest. (U.S. Secret Service, U.S. Department of Education)

96 – The percentage of school shooters who are male. (FBI records)

17 – The number of kids aged 15 or younger who have committed or attempted a mass school shooting since Columbine. (FBI records)

81 – The percentage of school shootings where someone had information that the attacker was thinking about or planning the shooting. (U.S. Secret Service, U.S. Department of Education)

68 – The percentage of school shooters who got their guns from relatives or at home. (US Secret Service, US Department of Education)

65 - The number of school shooters and thwarted school shooters who have referenced Columbine as a motivation. (ABC News investigation, various law enforcement agencies)

270 – The number of shootings of any kind at a school since Columbine. (ABC News review of reported cases)

1 – The number of shootings per week, on average, on a school or college campus in 2015. (ABC News review of reported cases)