180130-N-TP832-023 JACKSONVILLE, Fla. (Jan. 30, 2018) Master-at-Arms 2nd Class Marcus Perkins, right, gives evacuation instructions during an active shooter drill at Naval Station Mayport’s base chapel as part of Exercise Solid Curtain-Citadel Shield (SC-CS) 2018. SC-CS is an annual anti-terrorism force protection exercise designed to train Navy security forces to respond to the changing and dynamic threats to installations and units. (U.S. Navy photo by Mass Communication Specialist 2nd Class Michael Lopez/Released)