WASHINGTON - The Mid-Atlantic region battled a heavy, wind-driven snowstorm on Saturday that left over a foot on the ground in many places and forced people to take shelter and stay off highways from Virginia to New England.

Some power outages were reported in Virginia and Maryland, especially in Annapolis and on Maryland's eastern shore. Snowplows appeared to have kept many major roadways clear, although Washington's Capital Beltway at the U.S. 50 interchange was clogged with disabled or stuck cars.

Transportation officials had urged people to avoid driving, and most seemed to have heeded the warnings: Most Washington, D.C., streets were deserted at dawn, and traffic was minimal.

In downtown Washington, a foot of snow had fallen by 5 a.m., with more reported in the Virginia and Maryland suburbs.

The National Weather Service forecast map was red with blizzard alerts from the Blue Ridge Mountains to the Chesapeake Bay.

Wind restrictions were in place on the Chesapeake Bay Bridge, as gusts over 40 mph tore at flags, and downed wires blocked some streets.

The Saturday forecast called for heavy snow and higher winds out of the north. An additional foot of snow was possible. Thunder and lightning were also reported.

Off the coast, where the low-pressure system fueling the snowstorm was churning, wind gusts as strong as 60 mph were expected with towering ocean waves of 30 feet in height.

"As we await the latest model data to get a better idea on how much snow is left...we're on the lookout for official blizzard conditions," Dan Stillman of the Capital Weather Gang reported.

A blizzard requires "snow and/or blowing snow reducing visibility to [1/4] mile or less for 3 hours or longer and sustained winds of 35 mph or greater or frequent gusts to 35 mph or greater" according to the National Weather Service, he wrote.

Meanwhle, as the storm raged, District police had to search for a 9-year-old boy who went missing Friday afternoon in Northeast Washington. Police said Di'Marco Dempsy went missing about 4 p.m. Friday from his home in the 4900 block of 12th Street NE.

Saturday morning, police reported that Di'Marco was found safe and unharmed.

According to the National Weather Service, the record for the biggest two-day snowstorm in Washington was set Jan. 27-28, 1922, when 26 inches fell, collapsing the roof of the Knickerbocker Theater in Adams Morgan, killing more than 100 people.

The current storm grew in power just after midnight Friday. By 2 a.m. Saturday, snow was falling so fast that the National Weather Service issued a special statement that said the pace of the snowfall, as well as heavy wind gusts, were creating near whiteout conditions.

"Expect snowfall rates of up to 2 inches per hour within this band," the statement said.

People had already taken to social media at that hour to report snowfall totals between 9 and 11 inches.

The region shut down on Friday as the winter storm of potentially history-making magnitude swept in with the prospect of lasting 36 hours and leaving more than two feet of snow in some places. Cleanup from the storm is expected to take days.

The snow's arrival found Washington and its suburbs as prepared as they could be after days of warnings that this was a massive storm. Despite the hyperbole used before for many storms, this one genuinely looked like it would be the storm of the young century for the region - and perhaps one that would be remembered for generations.

By midnight, five to eights inches had already fallen, except in areas area Fredericksburg to southern Maryland, which had totals from eight to 10 inches. That was on track with the latest forecast from The Washington Post's Capital Weather Gang, which called for a total of 16 to 30 inches.

Hundreds of plows and salt trucks took to the major roads in Maryland and Virginia even before the snowfall began. But with the snow expected to keep falling as fast as three inches an hour, it seemed a matter of time before even those big arteries would be shut down.

With temperatures just below freezing, the snow was heavy with moisture, and the forecast of gale force winds posed a threat to trees and power lines, raising fears that snowbound residents would be left in the dark and without heat.

Pepco, which provides power to the District and much of the Maryland suburbs, warned customers that they may face multi-day outages. Dominion Virginia Power, which serves Northern Virginia, had similar fears.

"We began advising our customers earlier this week to prepare for a multi-day outage event. It's always best to prepare for the worst," said Dominion spokesman David Botkins. "With that said, we will be swarming the affected areas with crews to get the lights and heat back on as quickly and safely as possible."

As of dawn Saturday, however, power remained on for most customers in the Washington area.

From the outset, the snow readily took hold on pavement and parked cars that had been in near or below freezing temperatures all week.

Government officials and police agencies had warned residents to gather supplies and stay off the roads.

By 5 p.m. Friday, conditions began to deteriorate rapidly, and D.C. Mayor Muriel E. Bowser urged stragglers to get off the streets. She said the District National Guard had reported for duty and would be deployed to transport personnel around the city as needed.

"We have a forecast that we haven't had in 90 years," Bowser (D) said. "It has life-and-death implications, and all the residents of the District of Columbia should treat it that way."

Virtually all institutions and attractions in and around the capital region - including the Smithsonian museums and the National Zoo - said they would be closed through the weekend. Metro said it did not plan to resume bus and rail service until Monday.

Though the region's three major airports said they would remain open, airlines already had canceled hundreds of flights in and out of them. Amtrak said it hoped to operate on a reduced schedule along the Northeast Corridor line but encouraged would-be passengers to check before heading to the train station.

District officials said they were well staffed with emergency personnel but cautioned that responses might be delayed.

City officials warned residents that the city will be dealing with cleanup throughout the coming week and said residents should not expect to see snow plows before Sunday.

Maryland Gov. Larry Hogan (R) echoed that call for patience, saying it would take time for crews to clear the snow.

"We're not magicians," he said. "We can't make it disappear."