Number of K-12 school shootings U.S. 1970-2022, by active shooter status

As of June 2022, there were 153 school shootings in total in the United States in that year. Of these incidents, only two were active shooter incidents. The largest number of active shooter incidents in schools was in 2018, with 11 active shooters.
The source defines a shooting as any time a gun is brandished, fired, or a bullet hits school property for any reason.