BOSTON—Gusty winds and falling temperatures plunged the East Coast into a deep freeze Sunday as people started digging out after a powerful nor’easter dumped mounds of snow, flooded coastlines and knocked out power to tens of thousands. Dangerous wind chills fell below zero in many locations across the region after the storm dumped snow from Virginia to Maine. Philadelphia and New York had plenty of snow, but Massachusetts bore the brunt of the storm, with the neighboring towns of Sharon and Stoughton getting more than 30 inches of snow before the storm moved out. More than 100,000 lost power at the height of the storm, mostly in Massachusetts. The outages in Massachusetts had dropped to fewer than 50,000 by mid-day Sunday, mostly on hard hit Cape Cod. No other states reported widespread outages. Utility Eversource said Sunday it had 1,700 crews working to restore electricity in Massachusetts, and expected everyone …