How active-shooter training has changed in schools since Sandy Hook
(World News USA)

The learning curve got steeper and intensified after the 2012 massacre at Sandy Hook Elementary School in Newtown, Connecticut, where 20 young children and six faculty members lost their lives when a 20-year-old outsider shot his way into the school. The end result: 20 states now have specific laws requiring `lockdown` drills in all public schools, and 30 states have broad emergency plans that may encompass lockdowns. ......