The sight at Athens High School is an all-too-real scenario for law enforcement, but the guns were simulators, responding officers moved slowly and methodically, and the shooter holed inside the classroom was a veteran cop and instructor.

The Dallas Morning News observed Advanced Law Enforcement Rapid Response Training (ALERRT) in June at the school about 70 miles southeast of Dallas. ALERRT provides agencies nationwide with research-based active shooter response training and was named the national standard by the FBI. Dallas, Houston and San Antonio police have all adopted the curriculum.

On the first day, the training broke down each component of the proper response: The outside approach and breach, hallway maneuvers, the doorway entrance and what to do in the aftermath. The next day, the officers pushed through the training as one event without breaks.