In 2005, a 16-year-old killed seven people at his Minnesota high school by walking through the front door metal detector and fatally shooting a guard.
In a 1998 shooting in Jonesboro, Arkansas, two students pulled a fire alarm and began sniping people as they filed out to the parking lot, killing five and wounding 10 others.
All in all we had more school shootings in the 90's than we have now. There are 55 million students is the U.S and in the past 25 YEARS about 10 students per year are killed by gunfire at school. In comparison an average of 30 students per year are killed by school busses and or by falls. So no, as much as some might want you to believe it, Trump didnt invent school shootings.