Okay Public Schools is a tiny rural district in Okay, Okla. It has one K-8 school and one high school on a single campus of about 420 students. Its superintendent, Charles McMahan, just took a new step that he thinks will be a deterrent to violence: signs that warn visitors that some district staff are carrying guns — and are ready to use them.

Last year, school officials set a policy allowing specially trained staff members to carry guns on campus, an outgrowth of a 2015 law passed in Oklahoma and signed by Gov. Mary Fallin (R) legalizing the arming of teachers and staff on K-12 campuses.

The signs on the Okay schools campus now say, the Tulsa World reported:

Please be aware that certain staff members at Okay Public Schools can be legally armed and may use whatever force is necessary to protect our students.

Tulsa World quoted McMahan as saying:

“Having a sign in your front yard saying ‘this is a gun-free zone’ just tells the idiots, ‘Come on in because we can’t defend ourselves’ … “(Okay’s) sign might be enough to send somebody down the road looking for some other soft target. If that’s what it does, it’s helping our school district out.”

Okay is one of a growing number of districts across the country that either have or are considering arming adults in the belief that this will make schools safer in the event of an attack — even though there is no evidence proving that is the case.

In Ohio, for example, WKRC-TV reports that nearly 40 school districts now allow teachers to carry guns into class if they have permits. NBC reported recently that “legally gun-owning adults are now allowed to carry guns in public schools in more than two dozen states, from kindergarten classrooms to high school hallways,” and “seven of those states specifically allow teachers and other school staff to carry guns in their schools.”  In December 2015, the Keene Independent School district in Texas voted to allow teachers to carry guns.

The decision to arm adults in schools comes amid a growing number of firearm attacks on K-12 campuses. According to Everytown for Gun Safety Research, there has been at least 165 school shootings across the United States since 2013, with more than one a week in 2015 alone. (These include cases in which a gun was fired but nobody was hurt.)

A 2015 study from Ball State University in Indiana, titled “Reducing the Risks of Firearm Violence in High Schools: Principals’ Perceptions and Practices,” looked at how high school principals across the country perceive the problem of gun violence on campus and possible solutions — and it found a lot of confusion. The abstract says:

Principals perceived inadequate parental monitoring (70 %), inadequate mental health services (64 %), peer harassment/bullying (59 %), and easy access to firearms (50 %) as the main causes of firearm violence in schools. The three barriers to implementing firearm violence prevention practices were: lack of expertise as to which practices to implement (33 %), lack of time (30 %), and lack of research as to which practices are most effective (30 %). Less than half of schools trained school personnel regarding firearm violence issues. The findings indicate that firearm incidents at schools may be more common than previously thought. A significant portion of principals are at a loss as to what to implement because of a lack of empirical evidence on what is effective. More research is needed to find the most effective school interventions for reducing firearm violence.