HARTFORD, Conn. — A massive winter storm roared into the East Coast on Thursday, threatening to dump as much as 18 inches of snow from the Carolinas to Maine and unleashing hurricane-force winds and flooding that closed schools and offices and halted transportation systems.Forecasters expected the storm to be followed immediately by a blast of face-stinging cold air that could break records in more than two dozen cities and bring wind chills as low as minus 40 degrees this weekend.Blizzard warnings and states of emergency were in wide effect, and wind gusts hit more than 70 mph (113 kph) in some places. Eastern Massachusetts and most of Rhode Island braced for as much as 3 inches of snow per hour.Four people were killed in North and South Carolina after their vehicles ran off snow-covered roads, authorities said. Another fatality was reported near Philadelphia when a car could not stop at the bottom of a steep, snow-covered hill and slammed into a commuter train.