By Allen G. Breed and Jennifer PeltzNEW YORK -- From Washington to Boston, big cities and small towns Sunday buttoned up against the onslaught of a superstorm that could endanger 50 million people in the most heavily populated corridor in the nation, with forecasters warning that New York could get slammed by a wall of water. "The time for preparing and talking is about over," Federal Emergency Management Administrator Craig Fugate said as Hurricane Sandy made its way up the Atlantic on a collision course with two other weather systems that could turn it into one of the most fearsome storms on record in the U.S. "People need to be acting now." Airlines canceled more than 5,000 flights, and Amtrak began suspending train service across the Northeast. New York and Philadelphia moved to shut down their subways, buses and trains Sunday night and announced that schools would be closed on Monday. Boston, Washington and Baltimore also called off school. And nonessential government employees in the nation's capital were told not to report for work in the morning. As rain from the leading edges of the monster hurricane began to fall over the Northeast, hundreds of thousands of people from Maryland to Connecticut were ordered to evacuate low-lying coastal areas Sunday, including 375,000 in lower Manhattan and other parts of New York City, 50,000 in Delaware and 30,000 in Atlantic City, N.J., where the city's 12 casinos were forced to shut down for only the fourth time ever. > > Bull or Bear? Vote in Our Poll "We were told to get the heck out. I was going to stay, but it's better to be safe than sorry," said Hugh Phillips, who was one of the first in line when a Red Cross shelter in Lewes, Del., opened at noon. "I think this one's going to do us in," said Mark Palazzolo, who boarded up his bait-and-tackle shop in Point Pleasant Beach, N.J., with the same wood he used in past storms, crossing out the names of Hurricanes Isaac and Irene and spray-painting "Sandy" next to them. "I got a call from a friend of mine from Florida last night who said, 'Mark, get out! If it's not the storm, it'll be the aftermath. People are going to be fighting in the streets over gasoline and food.'"