They've begun counting any shooting that has 3 or more victims I think.
Probably. IMHO, intent matters.
I just read a news report from somewhere about a Memorial Day BBQ that went bad. IIRC, it was sort of a neighborhood/block party sort of situation. Two groups "got into it," shots were fired. Don't remember now if it was four wounded and one killed, or one wounded and four killed. What absolutely amazed me was that the local authorities specifically said, "This was not a mass shooting. This was two groups of people who engaged in a gunfight."
And, of course, that's exactly what it was. So I didn't add that one to my list. I'm sure the Brady Bunch and their ilk did add it to their lists.