What is the definition of a mass shooting?

https://usafacts.org/reports/facts-in-focus/domestic-terrorism-mass-shootings-data
https://github.com/USAFacts/betadata/tree/master/fbi_active_shooter
I am playing with the data from 2000-2018 that's on this site. I think these are only ones reported to the FBI. Not all. Or it is only "active shooters", not all mass shootings. Not sure how they split that hair.

They have 281 incidents listed, but only 271 where someone was shot (injured or killed).

If I use 10 casualties (injured and killed combined), there would be 48 incidents.

If I use 20 casualties, there are 13 incidents.

Those 13 incidents (which are all from 2007 to 2018) had 1036 casualties, 269 being murders. Every shooter in this group was a male. Handguns were the most commonly used weapon, followed by a rifle. 3 incidents using a rifle, also had handguns. Six out of the top 8 body counts, used a rifle (or multiple rifles). Almost half were in a school.

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