How technology helped prevent further bloodshed at Apalachee [Video]

Apalachee High School teacher Stephen Kreyenbuhl knew something was wrong Wednesday before he heard gunshots.

The social studies teacher told CNN he was in the middle of a lesson when his smartboard alerted that the school was in a “hard lockdown.”

“In that instance, I knew something emergency-wise was about to happen,” Kreyenbuhl said. “I got everybody into a corner, turned off the lights, and just kind of held everyone nice and tight and just said, ‘Wait for everything to happen, everything to pass.’”

Kreyenbuhl said the school’s new alert system bought him critical time to prepare and protect his students before a shooter opened fire just down the hall from their classroom.

“I was so happy to hear the voice of our (school resource officer) outside the hallway within about two minutes of the gunfire,” he said.

The CrisisAlert system, designed by Centegix, includes a device the size of …