(CBSNews) -- A massive pre-winter storm brought snow, sleet and freezing rain across a wide swath of the South on Sunday, causing dangerously icy roads, immobilizing snowfalls and power losses to hundreds of thousands of people. Accidents on snow-covered interstates caused major delays, hundreds of flights were canceled and drivers in North Carolina and Virginia got stuck in snow or lost control on icy patches.

Meanwhile, kids and the young at heart took advantage of the early winter snow with snowball fights, sledding and building snowmen.

Police in North Carolina and Virginia said they responded to hundreds of snow-related traffic accidents as of Sunday afternoon, as cars, trucks and tractor-trailers all struggled with the snow and ice.

North Carolina Gov. Roy Cooper strongly urged residents to stay off the roads Sunday, asking drivers not to put lives of first responders needlessly at risk. Cooper said emergency crews, including the National Guard, worked overnight to clear traffic accidents on major roadways.

"Stay put if you can," Cooper said. "Wrap a few presents, decorate the tree, watch some football."

Five members of a dive team searched the Neuse River in Kinston, North Carolina, for a missing truck driver Sunday after a tractor-trailer ran off a road and into the river, WRAL-TV reported. Police just outside of Charlotte said a driver died when a tree fell on a moving vehicle.

Governors and local officials in several states declared emergencies ahead of the storm crossing several Southern states, which hit portions of North Carolina and Virginia particularly hard.

Virginia State Police said Interstate 81 in far southwest Virginia was particularly dangerous, with snow coming down faster Sunday afternoon than crews could clear it. Police said several tractor-trailers slid off the highway.

Officials warned residents to prepare emergency kits and stay off roads in impacted areas. Several schools districts in North Carolina and Virginia announced they'll be closed Monday.

"Virginians should take all necessary precautions to ensure they are prepared for winter weather storm impacts," said Virginia Gov. Ralph Northam.

The National Weather Service said a "prolonged period of snow" began late Saturday and would last until Monday in the region, with the heaviest snow expected in northwest North Carolina and southern Virginia. Some areas of North Carolina and Virginia saw more than a foot of snow by Sunday afternoon.

Nearly 300,000 power outages were reported across the region, as of Sunday night, with the majority of those — about 145,000 — in North Carolina, according to poweroutage.us. Parts of Alabama, Georgia, South Carolina, Tennessee and Virginia also saw outages.

There were some 13,000 flights delayed and 1,795 canceled Sunday across the U.S., according to FlightAware.com. Travelers were advised to check their flight status before heading to the airport. Cancellations were reported on flights from as far as the Midwest.

Charlotte Douglas International Airport, the sixth busiest airport in the country, said American Airlines reduced its operations. The airlines issued a travel alert for nine airports throughout the Carolinas, Tennessee, and Virginia, meaning passengers may be able to change travel plans without a fee.

American Airlines told CBS News it has canceled 1,200 flights Sunday and 400 flights Monday. The company also said its Charlotte hub has limited operations Sunday night, but will begin to normalize Monday morning. "The majority of these cancellations will be on smaller, regional aircraft," American said.