Many students had the day off Monday because of President's Day, but some teachers in Lancaster did not.
They found themselves in the middle of terror, panic and simulated gunfire.
It was just a test, but the gunshots and screaming produced by a realistic shooting scene for training.
Volunteers, playing students and teachers running through the halls of Thomas Ewing Junior High School, made the active shooter training very real.
Officers practiced arriving on the scene and using tactics aimed at taking out the gunman.
“You can talk about it all-day long, but until you actually are in that situation, you don't know what will happen and what you need to do," said Shannon Webb, an actor.
The staff ran, hid and used fighting tactics. They practiced getting students to safety, locking them in a classroom and throwing things at the shooter, if they had no other alternative.
In the scenario, police officers were on the offensive to take out the marauding gunman.
"You always want to be as prepared as possible. You hope it never happens, but when it does, you want your staff and students to be as prepared as possible,” said Nathan Hale, director of human resources with Lancaster City Schools.
The district videotaped Monday’s drill, so officials can review the exercise and fine tune their response plan in case of a dangerous threat in a building.
"They're the folks on the front line, there before the officers. The decisions they make could affect people’s lives," said Lancaster Police Sgt. Mike Peters.
Watch 10TV News and refresh 10TV.com for more information.