as well as overseas -- reporter: chris conners is c.e.o. of shooter detection system. they took the technology and brought it into the classroom. it was first installed in a methuen school. now this technology is in a few dozen buildings across the area. >> the gunshot protection sensor that we installed, in the ceiling, in the wall. this is exactly what it looks like. very benign. i don't think anyone even saw it. that was the intent of the design. reporter: it uses both infrared and audio sensors. the company says it's 100% reliable, with no false alarms. this is only a drill. a gun is fired. instantly, the sensor identifies the location. that information is quickly sent to the police department, displaying on a map of the building. it shows the exact location of the gunfire. reporter: simultaneously, a all responding officers on their cell phones. inside. cutting down on the confusion, and they don't have to wait to enter a building. precious seconds that can save lives. >> how long does it take you to phone, call 911? dispatcher dispatcher calms you down. where ins