CHICAGO (CBS) – It was a startling scene outside Whitney Young High School as police surrounded the school with guns drawn and rescuers standing nearby. It was part of an active shooter drill, the first and largest drill of its kind at the school.

The principal at Whitney Young said she wants more training for staff after the most recent shooting in Parkland, Florida. Thursday, local authorities partnered with the school to hold a school shooter training exercise.

No students took part in the drill. 150 Chicago police recruits played the role of students. Chicago Police did not allow CBS 2 News inside the school to see the drill, saying they don’t want to reveal any of their emergency tactics.

On the outside of the school, there was a large presence of police, paramedics, and fire officials. CBS 2 News was told that there will be gunfire and paramedics will be staging injuries.

“The exercise will not only test the ability of the police to secure an area while an active shooter is out, but also test the fire department’s ability to render aid during an incident,” said Lieutenant Robert Stasch of the Chicago Police Department.

Chicago Authorities Prepare for Active Shooter Drill At Whitney Young

“We have 250 role players, 75 from the schools to replicate staff and techers, 150 police academy, and 40 students from the fire academy to replicate those injured,” said Richard Ford II, the First Deputy Fire Commissioner.

Whitney Young faculty and staff were given a choice to participate. About half of them chose to do so. The active shooter drill is the largest drill in all of Chicago Public Schools. CBS 2 News is told this drill will not be the last.