The Record
Every major U.S. school attack since Columbine, door by door.
Incident databases count attacks and victims. This one records what stood between each victim and the attacker: the door, its lock, its state, its glass. Every fact carries its source and a confidence grade. Filter it, drill into any incident, download it, and tell us what we got wrong.
Free to reuse under CC BY 4.0: credit ClassLock and link back.
Version · incidents · All of them are in the tally quoted on the Evidence page: the 19 major attacks researched first, 39 more from the ALERRT study, and 4 further events from 1999 and 2026.
Where the victims were
Deaths by what stood between victim and attacker
Rows graded secondary are included unless the box above is ticked. Rows whose location is not established are shown separately and never counted as behind a door.
Reading it
What the categories mean
Incidents
Click a row for the doors, the victims and the sources
K = killed, excluding the attacker. W = wounded by gunfire. "Lock defeated" means an attacker got through a locked classroom door by defeating the lock itself, as opposed to going through glass or an unlocked door.
| Date | School | State | Attacker | Where it began | K | W | How the attacker got into the building | Classroom doors (not the building entrance) | Glass breached | Classroom lock defeated |
|---|
Method
What is in the Record and what is not
- Sets. Every incident in the Record is in the tally quoted across this site. The 19 major attacks were researched first against their official investigations; 39 further events come from the ALERRT Center’s study of every K‑12 active shooter event from 2000 to 2025; 4 more, from 1999 and 2025–2026, were screened against the FBI’s active shooter definition (disputes, accidental discharges, targeted single-victim shootings and off-campus incidents are excluded). The Set filter shows each group on its own.
- Scope. Major U.S. K‑12 active shooter events from Columbine (1999) through September 2026 where the official investigation or best available account lets each death be placed relative to a classroom door. Virginia Tech is excluded as higher education. Attackers are excluded from casualty counts.
- Grain. One row per incident, with doors the attacker met and victim groups beneath it. Victims are grouped by outcome and location; no victim or attacker names are recorded.
- Grades. primary read directly from an official investigation, commission or prosecutor's report, sheriff's release, or the ALERRT study. secondary from news or an encyclopedic summary citing official sources, not re‑read against the document. unverified noted but not confirmed; shown in the drill‑down, never counted.
- Wounded. Official reports rarely place the wounded room by room. Where a count could not be placed it is marked "not established" and excluded from the door categories.
- Unknown is not no. A detector, a door state, glass or classroom entry that no source we read establishes is shown as "not established", never as "no". An incident with no door entries means no door interaction is established, not that none happened.
- Conflicts. Where sources disagree on a count or a weapon, the row follows the source named in its facts and records the conflict as a graded fact.
- Consistency. The site build recomputes the Evidence page tally from this file and fails if the two disagree, so the numbers quoted elsewhere on the site are always the numbers here.
Corrections and reuse
Tell us what we got wrong
Send corrections with a source to info@getclasslock.com with the subject "Record correction". Each release carries a version date; corrections are applied in the next release and noted in the research briefs that back this page.
Use it freely. The Record is published under the Creative Commons Attribution 4.0 license (CC BY 4.0). Copy it, republish it, chart it, put it in a board presentation, a news story or a product, commercial or not. The one condition: credit ClassLock and link to getclasslock.com/record.html.
Suggested credit: Source: ClassLock, "The Record: U.S. K‑12 active shooter events since Columbine, door by door," version , getclasslock.com/record.html (CC BY 4.0).
The license covers ClassLock’s compilation, coding and summaries. Material quoted from the official reports and studies cited on each row remains under its own terms.
Underlying sources are the official investigations cited on each row, the U.S. Secret Service National Threat Assessment Center studies, and the ALERRT Center's 2026 study of 54 K‑12 active shooter events. The ClassLock research briefs that compile them are available on request.