Was a lockdown justified in the Boston area last Friday in the hunt for a terrorist? NPR explores that issues. It is not unusual to lock down schools and other institutions when there are reports of gunfire. To shut down a large part of a metropolitan area is another thing, says Frank Cilluffo of the Homeland Security Policy Institute at George Washington University. “In terms of both scale and scope, the shelter-in-place that was enforced was extraordinary, perhaps even unprecedented, but so too were the circumstances,” he says. “The payoff to the would-be terrorists is the most disruption you can get,” says Stephen Flynn of Northeastern University’s George J. Kostas Research Institute for Homeland Security. “So on the one hand, you’re trying to obviously safeguard life and property. On the other, you want to make sure that you’re not creating, essentially, future motivation for follow-on attacks to take place because [of] the possibility [that] if you carry out one of these horrific acts, you can shut down a major city.” Flynn believes officials made the right call given the circumstances, noting there is no rule book for dealing with armed individuals who may be carrying explosives. The irony is that it wasn’t until the lockdown was lifted that a Watertown resident found Dzhokhar Tsarnaev hiding in a boat in his backyard.