The Columbine Attack
Columbine was intended primarily as a bombing, but the main bombs all failed. So the secondary weaponry of the guns became the main event. Eric Harris and Dylan each carried two big guns: a semi-automatic rifle, and a sawed-off shotgun.
Here are photos of all four, as well as the elaborate knives they toted. All photos were released by the Jeffco Sheriff's Department. I also included a screenshot from the Jeffco report showing how many rounds each killer shot, with each gun. Descriptions appear above each photo.