Metro-North Rail Road held a drill Saturday in Norwalk to ensure proper security in the case of an emergency. The goal of the drill was to see how well crews responded to an explosion on board a Danbury-Line Metro-North train. In the staged scenario, police, firefighters and paramedics swarmed Crescent Avenue in Norwalk, where a fake bomb had detonated on board a train. More than 100 passengers pretended they were injured. The wounded made their way through the fake debris. Metro-North workers are trained in this type of emergency. They know to move passengers who are not in need of EMT care, out of the way of responders. The drills are done over and over again, mixing in different scenarios. Next month, the agencies will meet and watch the tapes together to find out what areas need improvement.