Dylan Klebold and the 1999 Columbine High School Massacre
Background
Dylan Bennet Klebold was a 17-year-old senior at Columbine High School when he and fellow student Eric David Harris carried out a planned bombing and mass shooting on April 20, 1999. The attack occurred at Columbine High School in unincorporated Jefferson County, Colorado, near Littleton. Klebold and Harris murdered 12 students and teacher William “Dave” Sanders that day, wounded more than 20 other people, and then died by suicide inside the school library.
Klebold was born on September 11, 1981, in Lakewood, Colorado. He grew up in the Denver metropolitan area and attended Columbine High School with Harris. The two teenagers became close friends, worked together at a Blackjack Pizza restaurant, and participated in school video projects. Their outwardly ordinary activities concealed months of preparations for a large-scale attack against their school.
In January 1998, Klebold and Harris were arrested after breaking into a van and stealing electronic equipment near Deer Creek Canyon. They entered a juvenile diversion program that included counseling, community service, anger-management instruction, and restitution. Both completed the program early and were described as cooperative. Investigators later determined that their violent planning continued after their arrest.
Planning the Attack
The Columbine attack was intended to be more than a shooting. Klebold and Harris constructed numerous homemade explosive devices and placed two large propane bombs in duffel bags inside the school cafeteria. They expected the cafeteria bombs to explode during the busy lunch period, killing people inside and causing part of the library above it to collapse. They planned to shoot students and employees attempting to escape from the building.
The main cafeteria bombs failed to detonate as intended. After waiting outside the school, Klebold and Harris abandoned the original timetable and began shooting at approximately 11:19 a.m. on April 20, 1999. Klebold carried a semiautomatic pistol and a sawed-off double-barreled shotgun. Harris carried a carbine and a sawed-off pump-action shotgun. Both also possessed additional ammunition and explosive devices.
The Attack Outside the School
The shooting began near the school’s west entrance and outdoor staircase. Rachel Scott was killed while eating lunch outside with Richard Castaldo, who was seriously wounded. Daniel Rohrbough was killed near the staircase as students attempted to flee. Other students were shot and injured in the same area.
Klebold briefly entered the cafeteria before returning outside. He and Harris fired toward students, school windows, and responding officers. They then entered the building through the west doors. Teacher Dave Sanders encountered the developing emergency and worked to direct students away from danger. Sanders was shot in an upstairs hallway while attempting to warn and protect others.
The Library Murders
At approximately 11:29 a.m., Klebold and Harris entered the school library, where dozens of students and staff members were hiding under tables and behind furniture. Ten students were murdered in the library during an attack lasting only several minutes. Numerous others were wounded.
Klebold and Harris moved through the room together, firing beneath tables, threatening students, and setting off explosive devices. Investigators attributed five fatal shootings to Klebold: Kyle Velasquez, Matthew Kechter, Lauren Townsend, John Tomlin, and Corey DePooter. Harris was identified as the shooter responsible for the deaths of Steven Curnow, Cassie Bernall, Isaiah Shoels, Kelly Fleming, and Daniel Mauser. Regardless of which weapon caused each fatal wound, Klebold and Harris were jointly responsible for the entire planned attack and every death resulting from it.
The attackers left the library at approximately 11:36 a.m. They moved through hallways and returned to the cafeteria, where they attempted unsuccessfully to detonate the propane bombs. They eventually returned to the library. Shortly after noon, Klebold and Harris died by suicide near the library’s windows. Surviving students began escaping after the attackers left the library and again after their deaths.
Victims Killed on April 20, 1999
- Rachel Joy Scott, 17 — Killed outside Columbine High School near the west entrance while eating lunch with another student.
- Daniel Lee Rohrbough, 15 — Killed outside near the west staircase and sidewalk leading toward the school’s west entrance.
- William David “Dave” Sanders, 47 — A teacher and coach who was shot in an upstairs hallway after helping students escape from the cafeteria and directing them toward safety.
- Kyle Albert Velasquez, 16 — Killed inside the Columbine High School library.
- Steven Robert Curnow, 14 — Killed inside the library while sheltering beneath a computer table.
- Cassie René Bernall, 17 — Killed inside the library while hiding beneath a table.
- Isaiah Eamon Shoels, 18 — Killed inside the library while sheltering beneath a table with Matthew Kechter and another student.
- Matthew Joseph Kechter, 16 — Killed inside the library beneath the same table where Isaiah Shoels was murdered.
- Lauren Dawn Townsend, 18 — Killed inside the library while hiding with several other students.
- John Robert Tomlin, 16 — Killed inside the library after initially surviving an earlier burst of gunfire.
- Kelly Ann Fleming, 16 — Killed inside the library while sheltering beside a table.
- Daniel Conner Mauser, 15 — Killed inside the library after attempting to resist his attacker.
- Corey Tyler DePooter, 17 — Killed inside the library while hiding with other students.
Anne Marie Hochhalter
Anne Marie Hochhalter was 17 when she was shot outside the school during the April 20, 1999, attack. Her injuries left her partially paralyzed, and she experienced serious medical complications for the remainder of her life. Hochhalter died on February 16, 2025, at the age of 43. The Jefferson County Coroner’s Office determined that complications associated with her paralysis significantly contributed to her death and classified the manner of death as homicide. As a result, the official number of homicide victims connected to the Columbine attack increased from 13 to 14.
Investigation and Misconceptions
The massacre generated extensive investigations into Klebold and Harris, their preparations, their writings, and warning signs that existed before the attack. Evidence showed that the assault had been planned for months and was designed primarily as a bombing. The failure of the cafeteria explosives prevented a potentially much larger loss of life.
Early reporting often portrayed the attackers as members of a school group called the “Trench Coat Mafia” and described the massacre as a spontaneous act of revenge by bullied outcasts. Later investigations showed that these explanations were incomplete or misleading. Klebold and Harris had personal grievances, but they planned an indiscriminate attack against students, teachers, emergency responders, and the surrounding community rather than limiting their violence to particular alleged bullies.
Another frequently repeated story claimed that Cassie Bernall was asked whether she believed in God immediately before she was killed. Investigators concluded that this exchange involved wounded survivor Valeen Schnurr rather than Bernall. The correction became an important example of how confusion, trauma, and early media reports created lasting myths about the massacre.
Aftermath and Legacy
The Columbine High School massacre had a profound effect on American schools, law-enforcement tactics, emergency medical responses, media coverage, and public discussions about youth violence. Police agencies reconsidered the practice of waiting for specialized tactical teams during an active shooting and increasingly trained officers to enter buildings quickly to confront attackers.
Schools throughout the United States introduced or expanded lockdown drills, threat-assessment programs, anonymous reporting systems, security procedures, and emergency response plans. The massacre also became a disturbing reference point for later attackers, making responsible reporting and a victim-centered understanding of the event especially important.
The Columbine Memorial was established in Clement Park behind the school to honor those killed, those injured, the survivors, emergency personnel, and the wider community. Its Ring of Remembrance contains tributes to the 13 people killed on April 20, 1999. The victims are remembered as individuals with families, friendships, ambitions, and lives that extended far beyond the circumstances of their deaths.
Conclusion
Dylan Klebold was not merely a troubled student drawn into another person’s plan. The surviving evidence demonstrates that he knowingly participated in preparing explosives, acquiring weapons, selecting the school as a target, and carrying out the murders. His actions with Eric Harris on April 20, 1999, caused immediate death and injury, inflicted lasting physical and psychological harm, and permanently changed the Columbine community.
Although Klebold’s name remains closely associated with the massacre, the central legacy of Columbine belongs to the victims, survivors, families, educators, emergency personnel, and community members who endured its consequences. Remembering their names and experiences provides a more accurate and responsible account than allowing the perpetrators to dominate the history of the attack.
