Multiple studies have observed that the presence of armed school officers does not deter school shooters.
A 2021 study published by JAMA that examined 133 cases of intended or executed school shootings between 1980 and 2019 found "no association between having an armed officer and deterrence of violence." Authors explained that since "school shooters are actively suicidal, intending to die in the act, ... an armed officer may be an incentive rather than a deterrent." They also noted the "well-documented weapons effect," in which "the presence of a weapon increases aggression." Their research indicated that "an armed officer on the scene was the number one factor associated with increased casualties."
Another 2021 study published by Brown examining national school-level data from 2014 to 2018 found that while school resource officers "reduce some forms of violence in schools, [they] do not prevent school shootings or gun-related incidents." Such officers were also associated with increased suspensions, expulsions, police referrals and arrests of students—particularly Black students.
To deter school shootings, school safety researchers advocate: