An emergency drill at a high school on Long Island, to help police prepare for the possibility of a gunman gaining access to the school.
Police held the drill in West Babylon, simulating trying to locate a suspect who is opening fire in a classroom.
Of course the entire thing is just a drill, complete with sounds of children yelling and gunfire throughout the hallways.
"This could happen at any time on any given day so these officers need to know to be comfortable with the situation," said Suffolk County Police Deputy Inspector Mathew Lewis.
Suffolk County police have been doing these practice runs for the past few months, training all of their officers using school buildings to recreate an active shooter scenario.
This one took place at West Babylon High School.
School administrators also got to witness what would be one of their worst nightmares.
Police have turned the hallways into a whole bunch of obstacle courses.
They're using modified Glocks with fake 9mm ammunition.
There's no way to know if officers would ever need these skills
But parents and school administrators are surely happy they're learning them.
"If an incident were to happen in our schools, the local precinct they actually know the lay of the land of our schools," said West Babylon Superintendent Anthony Cacciola.
"Knowing that the police can come in and go through the building. know what our weak points are it makes me feel safer," said parent Diane Thiel.