School districts trying to avoid becoming next on the list are urgently chasing answers, with an increasing number staking their hopes on high-tech security systems originally developed for the military, police and private industry.
These modern tools range from instant background checks for visitors and social-media monitoring software to gunshot-detection sensors and ID cards equipped with panic buttons. They’re driving a rapidly growing school security market, which has ballooned to a multibillion-dollar industry — despite little proof that the new methods prevent violence.
