Some may find it interesting to review information from the Secret Service National Threat Assessment Center on school safety.
Buried in all of the verbiage it the suggestion of having a police presence on campus, even where a full time School Resource Officer is not in place.
"Where school resource officers are not present, encourage law
enforcement personnel to have a presence in the school, such as having lunch in the cafeteria or completing administrative
work in the school library, a patrol car in the school parking lot, or even an empty office."
https://www.secretservice.gov/data/p...018_Update.pdf
Another interesting report, regarding mass attacks in public spaces in 2017, contained the interesting fact that "over three-quarters of the attackers made concerning communications and/or elicited concern from others prior to carrying out their attacks. On average, those who did elicit concern caused more harm than those who did not."
Great data with graphs.
https://www.secretservice.gov/data/p...paces-2017.pdf