1700s The earliest known United States shooting to happen on school property was the Pontiac's Rebellion school massacre on July 26, 1764, where four Lenape American Indian entered the schoolhouse near present-day Greencastle, Pennsylvania, shot and killed schoolmaster Enoch Brown, and killed nine or ten children (reports vary).
Again, most of those are targeted attacks on individuals. E.g. student mad at X person and gets revenge.
Much different from the columbine-like terroristic ones. E.g. killing anyone and everyone they can.