The NYPD and FDNY simulated an active shooter situation on a school campus in Brooklyn Sunday morning, police said.

The planned exercise, which began at 6 a.m., took place inside Leon M. Goldstein High School for the Sciences on the Kingsborough Community College campus in Manhattan Beach, police said. The scenario involved multiple active shooters and improvised explosives, police said.

“Training today with our partner agencies so you can rest easy,” the NYPD tweeted on Sunday. The Department of Homeland Security and New York City Emergency Management also took part in the exercise, police said.

Police urged locals on Twitter not to be alarmed at the sight of an increased number of first responders in the area.

“Just a drill!” The NYPD tweeted. “But NYPD & our partners training now in Brooklyn to continue protecting NYC.”