It usually goes like this. A school will receive an anonymous call or is tipped off to a social media post threatening a shooting. The investigation could take anywhere from a few hours to a few days. But until schools are given the all-clear, these threats are virtually indistinguishable from the real thing in terms of the emotional and psychological impact.

In the past few months, schools across the United States have been experiencing just this scenario, and the trend doesn't seem to be letting up. The National Association of School Resource Officers (NASRO), has tracked at least 60 instances of fake school shooting threats or hoaxes – sometimes referred to as "swatting" – across 30 states and Washington, D.C., since September.