a swine flu outbreak that struck the mexico city region particularly hard. it killed more than 1,200 people in that country. that was 2009. four years later it was april 2013, and a city in this country chaim came to a standstill but for a very different reason. it was days after the boston marathon bombing before police officers found and engaged in a brutal gun battle with the suspected bombers. one of the terrorist attackers from the marathon bombing was killed in that shootout, but the other one managed to flee the scene. and while the active manhunt continued for dzhokhar tsarnaev the governor of massachusetts took unprecedented action. deval patrick gave a news conference at dawn in which he asked residents of the greater boston area to shelter in place indefinitely. and people did. from dawn until after sundown the city was deserted. public transportation was shut down. a temporary no-fly zone was imposed over the city.