The base sent us photos of the event.
Quantico: “Marine Corps Base Quantico is partnering with Prince William County to conduct a full-scale exercise on the base on May 25 that will simulate a train derailment on main side. The exercise, which is expected to be the largest conducted here in more than a decade, will test the ability of the base and Prince William County to react and work together in a multi-faceted emergency that affects the base and local community.”