An unarmed school is not safe.
Actually, Delawares gun violence has not taken place on high school or college campuses, and there are quite a few for a state population of not quite a million. Most of the instances have been within the inner city limits, but outside the schools.
Most of the excuses for instituting greater infringements of the Second Amendment have been figments of the imaginations instituted by parties longing to achieve greater control of the population, part of it being a neurotic fear of guns in those who have never possessed, been trained in, or used firearms in sporting or self-protection purposes. They are simply not aware that where gun controls are implemented, those who are criminally minded only see that as a greater opportunity for their use on an unarmed population.