https://www.npr.org/sections/ed/2018/08/27/640323347/the-school-shootings-that-werent
and...
That is a truly terrifying and apparently flat-out fabrication of data. That data was from 2015-16 school year.
But NPR reached out to every one of those schools repeatedly over the course of three months and found that more than two-thirds of these reported incidents never happened.
and...
In 161 cases, schools or districts attested that no incident took place or couldn't confirm one. In at least four cases, we found, something did happen, but it didn't meet the government's parameters for a shooting. About a quarter of schools didn't respond to our inquiries.
That is a truly terrifying and apparently flat-out fabrication of data. That data was from 2015-16 school year.