Have to question the basic accuracy of that Wikipedia entry from the off.
"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 Indians entered the schoolhouse near present-day Greencastle, Pennsylvania, shot and killed schoolmaster Enoch Brown, and killed nine or ten children (reports vary). Only three children survived."
An event which pre-dates the existance of the USA by 12 years. An error which is so basic it makes the complicated rest questionable.
(, Sat 15 Dec 2012, 12:53, Reply)