A former substitute teacher in the Baraboo School District has invented a gunshot alarm system which would alert people in a building to the sound of gunfire, while simultaneously notifying emergency responders. The concept is similar to a standard fire alarm. Sensors set off the alarm when they detect and confirm the sound of a gunshot. Those sensors help emergency responders by pinpointing the exact location of the sound. Stacy Jax started working on her idea after the deadly 2012 mass shooting at Sandy Hook Elementary School in Connecticut. The Trinity Gunshot Alarm System was tested last week at an indoor shooting range.