Eight thirty a.m., an explosion rocks Addison High School. Soon after, three gunmen enter the school.
Multiple gunshots can be heard ringing through the school's two main hallways, and a number of wounded students line the hallway floors.
Within a few minutes, four police agencies arrive on the scene, locate and kill the shooters, and call for medics to deal with the injured.
All of these events actually happened Thursday morning, but nobody was in any apparent danger. This nightmarish situation was a drill, organized by the school and police, along with a number of emergency responders.
The drill allowed each the opportunity to practice how to respond to an active gunman during a realistic simulation.
"When I looked in the classroom I couldn't see anything because the teachers had the kids in the corners," said Greg Morenko, a Michigan State Police Sergeant who played the role of gunman in the school during the drill.
Morenko says this drill will serve the entire district well in terms of emergency readiness.
"If God forbid it does happen, they'll be prepared for it," Morenko said, "the more realistic it is the more the kids are going to learn from it."
"We've been trained not to open doors. We've been told if they need to get in, they'll have a key to get in," said teacher Aaron Wesche.
Wesche barricaded and locked his doors and kept his students in the corner of the room, as the "gunmen" knocked on the outside of his door. Though the gunmen tried to identify themselves as police, Wesche never opened his door, which, according to police, was the right thing to do.
"You did feel the intensity around it. The kids did awesome, they took it seriously from the very start," said Wesche.
From Columbine to Newtown, First Lieutenant Tony Cuevas says school shootings can happen anywhere, and it pays for all districts to be ready.
"There's no rhyme or reason why these locations are chosen. You have to be prepared everywhere, students and staff have to be thinking about this," said Cuevas.