WILLIAMSON COUNTY, Tenn. (WKRN) – It’s America’s worst nightmare, an active school shooter roaming a school filled with frightened kids trapped in classrooms.

With law enforcement descending from all points of the map to neutralize the threat, chances are good in rural counties that those first responders will be engaging the school shooter alone.

To practice for that heart stopping scenario, all this week the Williamson County Sheriff’s Office is training officers from the Tennessee Highway Patrol, Nolensville Police Department, Fairview Police Department, and Franklin Police Department on how to move safely and efficiently through a large high school where hiding places for a would-be sniper are everywhere.

Sheriff’s deputies conducting the training broke down the hallways, stairwells, cubbies and classrooms as geometric patterns and zones.

Instructors talked about angles and distances and effectively clearing zones while always moving toward the threat.

Training officers reminded their students how to stand, what to look for, even how to hold their guns as they scanned the hallways for trouble, with the main goal of neutralizing a would-be killer whose target is children.

“He is likely by himself. Everyone is coming, but we have to come from miles around,” Williamson County Sheriff Dusty Rhoades said.

According to Rhoades, if there’s an active school shooter in smaller communities, everybody’s coming, but nobody’s waiting. What that means is the first officer on scene has a mission to neutralize the shooter.

“What you will see here, especially in your rural areas, you will see one officer, maybe two on a good day, arrive on a scene, and it is going to take everything we got, but the first ones on the scene are the most crucial. They got to get in and stop the threat, and most times it is one officer, maybe two,” Rhoades said.

According to Rhoades, there are 60 schools in Williamson County, and every school in the county has at least one SRO.