650,000 without power as blizzard heads out to sea NEW: At least four people died in traffic accidents related to the storm in NY, CT and Ontario NEW: Dozens slept in a firehouse in Middle Island, New York, after getting caught in the storm New York Gov. Andrew Cuomo plans to send snow plows to New England Flooding concerns force mandatory evacuations along coast in Massachusetts New York (CNN) -- A massive blizzard that dumped as much as 3 feet of snow in parts of the Northeast is heading out to sea, as workers across New York and New England struggle to get airports, trains and highways back online. The snowstorm, a product of two converging weather systems, knocked out power for more than 650,000 customers and prompted the U.S. Postal Service to suspend deliveries in seven states. At least four people died in traffic accidents related to the storm in New York, Connecticut and southern Ontario, authorities said. Mandatory evacuations were issued Saturday morning for Massachusetts coastal regions near the town of Hull because of flooding concerns, and high winds whipped throughout the region. Authorities also advised residents to leave shoreline areas in Marshfield and Scituate. Forecasters say the storm is still expected to swirl across eastern New England with gusts up to 40 mph in cities that include Providence, Rhode Island, and Boston. Most of the heavy snow will taper off later in the afternoon. While the blizzard did not fulfill predictions of historic proportions, travel throughout the region remained slow-going. Three of New York's busiest airports resumed limited service Saturday morning. Logan International Airport in Boston and Bradley International Airport in Windsor Locks, Connecticut, stayed closed. "We're slowly coming back," said Susan Baer, Port Authority aviation director of New York and New Jersey. We don't have every runway open yet and it's certainly a recovery process, so check with your airline. Snowfall in Manhattan reached just under a foot, with heavier accumulations in Long Island, where 27 inches fell in Stony Brook. "This state had consequences, but nothing like our neighboring states," said New York Gov. Andrew Cuomo. He announced Saturday plans to send utility workers and snow plows to New England in an effort to help with recovery in harder hit areas. Connecticut saw the most accumulation with up to 38 inches in cities like Milford, while the Massachusetts cities of Worcester and Boston received 27 and 21 inches, respectively, with winds howling up to 75 mph. The storm knocked out power to more than 400,000 addresses there, accounting for nearly two-thirds of all power outages, according to Massachusetts power companies. Plymouth is 90% in the dark, and most of the power outages in Massachusetts have hit the southeast portion of the state. Rhode Island may have seen the worst outages relative to its size, with more than 180,000 customers without power. At 1 million residents, it has only one-sixth of Massachusetts' population, according to the U.S. Census Bureau. Gov. Lincoln Chafee on Saturday ordered all non-emergency vehicles off the streets in an effort to allow snow plows to clear roadways. Snowfall blanketed an area from eastern Pennsylvania to Maine, with overnight lows under 20 degrees as governors in six states declared states of emergency. At its height, the storm heaped snow on Connecticut at a frenzied rate of 4 to 5 inches an hour. iReporter Scott Green posted a photo of his deck in Cromwell covered waist-high with snow. But the nor'easter also showed some mercy. Instead of carrying its destructive power further inland the way Superstorm Sandy did in early November, it pushed off shore. The nation's attention is now expected to shift to the plains and mountain states, where blizzards and heavy snows are expected Monday over a far less populous region. Massachusetts, Connecticut and Rhode Island ahead of the storm ordered all non-emergency vehicles off the streets under threat of imprisonment and fines -- up to a year in jail and $500 in Rhode Island. Those closures remain in effect. In Poughkeepsie, New York, an 18-year-old woman lost control of her car in the falling snow and struck a 74-year-old man walking near the side of the road, police said. He later died from his injuries. Similar accidents occurred in Prospect, Connecticut and southern Ontario. Hundreds of cars were stranded on the Long Island Expressway after motorists got stuck driving in the snow. They outnumbered the tow trucks and crews deployed to the area for the storm, according to the Suffolk County police. Postal worker Karlene Calliste left her job around 3 p.m. Friday, got caught in the storm and ended up sleeping at a firehouse in Middle Island, New York, where dozens of other stranded residents were holed up. It's crazy. They weren't prepared," she said, adding that a lack of snow plows contributed to the scores of cars and trucks left stuck in the snow. Hoops snowed out The Knicks are stuck in Minneapolis, where they played the Timberwolves on Friday, a spokesman said. They have a home game at Madison Square Garden on Sunday against the L.A. Clippers. Canceled flights forced the Nets to attempt to get home by train from Washington after a game there against the Wizards. The San Antonio Spurs, who were originally flying to New York to play the Brooklyn Nets on Sunday night, are stuck in Detroit. CNN's AnneClaire Stapleton, Pauline Kim, Jake Carpenter, Greg Botelho, Chris Boyette and Marina Carver contributed to this report. David Ariosto is in New York and Ben Brumfield is in Atlanta.