A bomb scare emptied the nation’s busiest commuter rail station Sunday for about an hour, disrupting service on trains and subways. The midday threat at Pennsylvania Station arose after someone threw a backpack at an Amtrak ticket agent and said it was a bomb, said Marissa Baldeo, a spokeswoman for New York City Transit. It was a false alarm, and service on all lines was restored by early afternoon. Amtrak spokeswoman Sarah Swain said railroad police had detained a man, but she did not know whether he had been arrested. Full Story