As a professional who spent years working with police departments in New York, New Orleans and Philadelphia on profiling criminal snipers, I am keenly aware of the problem of guns in our society. I am also aware of the problems associated with people who legally carry weapons in public spaces.
In spite of recent interest in arming teachers and other school personnel as a response to school shootings, I know that the scenario of armed civilians in the middle of a shooting incident is a prescription for disaster.
Once the Emergency Services Unit or a SWAT team shows up on site, they will be confronted with the difficult dilemma of determining who should and who shouldn't have a gun. In the chaos of the moment, it would be easy to mistake a "good person with a gun" for a "bad person with a gun." As a result, the likelihood of civilians getting hurt increases exponentially.
I'd like to impress upon the reader that the idea of putting more guns in schools will likely result in more harm than good.