1764
July 26 – In what is described 250 years later as "The first documented United States school shooting",[16] a group of four Delaware Indians invade a schoolhouse near what is now Greencastle, Pennsylvania and kill ten schoolchildren and their teacher, Enoch Brown.[17] The massacre happens in the course of Pontiac's War, as retaliation against white settlement of Indian lands in central Pennsylvania. One student, Archie McCullough, manages to escape the carnage; a memorial is erected 120 years later on August 4, 1884.
https://en.wikipedia.org/wiki/1764