In the long term, there is just one answer to the problem of school safety: more love. The short term solution, on the other hand, lies in the unhealthy mix of force, fear, guns, security, locks, and other devices meant to barricade our children from a small, but obviously lethal, subset of the population.
I'll leave the short-term answers to parents and politicians. Instead, let's support advances in education that take us closer to the ultimate goal of raising, nurturing, and educating children who feel psychologically safe. That, really, is the sole purpose of whole child education.