People cross a street as it snows in Washington, January 20, 2016. Icy roads and freezing temperatures prompted school closings and emergency preparations in several states in the US South on Wednesday, as snow began to fall on some areas ahead of a major storm expected to blast snow across the Northeast later this week. [Photo/Agencies]

WASHINGTON - Washington D.C., New York and other East Coast cities readied fleets of snow plows, thousands of flights were canceled or delayed and residents stocked up on groceries on Thursday ahead of a winter storm expected to dump up to 30 inches (76 cm) of snow on the region.

At least five states had declared emergencies by Thursday afternoon, as the season's first major Atlantic Coast storm started to move over the Mid-South before barreling on an expected north and eastward course bringing up to two feet of snow to some areas.

Blizzard warnings were out in the nation's capital and Baltimore, with extreme conditions expected to begin on Friday afternoon, while New York City was under a blizzard watch for Saturday morning.

The Washington Metropolitan Area Transit Authority, which includes the second-busiest US subway system, said it would suspend operations from late on Friday through Sunday.

The Virginia National Guard said it planned to bring in up to 300 troops to assist in response operations.

Grocery store shelves were being stripped of bread, milk and other essentials as millions of residents in the storm's path prepared to hunker down for a wintry weekend. Consumer watchdogs warned against illegal price gouging for such essentials as generators, batteries, flashlights and hotel lodging.

Airlines began cancelling Friday and Saturday flights, with most of the 951 cancellations for Friday at Washington and North Carolina airports, according to FlightAware.com.

American Airlines Group Inc scrapped all Friday flights into North Carolina's Charlotte Douglas International Airport, and Delta Air Lines Inc canceled about 120 flights in the Southeast region. American scrapped most Saturday flights into Washington, New York and Philadelphia area airports, and Delta was poised to cancel many of the same.

Washington Mayor Muriel Bowser and New York Mayor Bill de Blasio urged motorists to stay off roads, starting on Friday.