Future first responders got valuable real-life experience Friday in emergency mass casualty simulations.

The responders worked alongside Nassau County Police Department Homeland Security.

The program, run by The Zucker School of Medicine at Hofstra and Northwell Health, gives students a chance to see how they'd respond in pressure-packed, life-or-death situations.

Simulations included an active shooter in a school, hazmat spill, terrorist attack and an LIRR train derailment.