They are just playing a numbers game. The important wording is “school-related” shootings. Not school shootings. It is a great way to puff the numbers as there are way more school-related shootings than school shootings.
When I was in the school business we had to report crime that occurred in a 10 mile radius of the school to the feds for school crime stats. I’m guessing that’s where these numbers come from but I have been out of that for a long time.
Bob