SAVANNAH, Ga. (AP) — Cities rolled out snow plows that hardly ever leave the garage, a hardware store sold feed scoops for use as snow shovels and alligators in the Okefenokee Swamp burrowed into mud to stay warm Tuesday as a winter storm brought snow, ice and brutal cold to the Deep South, a part of the country more accustomed to hurricanes.

As many as 50 million people across the region could be affected. By midday, light snow had started falling in Jackson, Miss., and covered buildings Atlanta, where about 900 flights had been canceled at the world's busiest airport. As far west as Austin, Texas, ice-glazed roads caused dozens of wrecks.

With the severity of the freezing blast uncertain, motorists from Texas to Virginia were warned to stay off the roads. Popular warm-weather tourist destinations — Charleston, S.C.; Savannah, Ga.; Pensacola, Fla.; Virginia Beach, Va.; and New Orleans — expected ice and snow over the next two days, rare occurrences in places that seldom even see freezing temperatures for long periods of time.

In Charlotte, N.C., Mike Hammond pushed a grocery cart filled with food to his car and looked at the ominous, gray sky.

"You never know what's going to happen," he said. "But I'm making sure I have the staples — and batteries for my flashlights in case something happens to the power. I want to be prepared."

Meanwhile, in the Midwest, plummeting temperatures and increasing winds took root for another day even as the storm moved south. Several states in the central U.S. saw schools and other facilities close for a second consecutive day as dangerous wind chills were predicted. In Minnesota, forecasters said wind chills could reach 35 to 50 degrees below zero.

At an Ace Hardware store in the north Georgia town of Cumming, snow shovels were in short supply, but manager Tom Maron said feed scoops — often used in barns — could be substituted.

"We're fixing to put the ice melt out, and we've got plenty of sand here to mix in," Maron said shortly before dawn.

In Savannah, residents braced for a winter whiplash, barely 24 hours after the coastal city hit a T-shirt friendly 73 degrees. Less than ¼ inch of ice and up to 1 inch of snow was possible in a city that hasn't seen much snowfall on its manicured squares in the last 25 years. Savannah had 3.6 inches of snow in December 1989, a dusting of 0.2 inches in February 1996 and 0.9 inches in February 2010.

Jason Deese with the National Weather Service said the snow totals would matter less than the ice potential.

In rural Mississippi, four people died when an early morning fire destroyed a mobile home in Itawamba County, near the Alabama border. Investigators believe a space heater was to blame as temperatures dipped to about 20 degrees overnight. Sheriff Chris Dickinson said nine people were in the mobile home at the time. Officials didn't identify the victims but said they ranged in age from 3 months to 30 years.

In Montgomery, Ala., Bradley Thrift sat in a hotel parking lot letting his truck warm up before heading out with a crew to work on sewers.

"We've got a job to do. We'll just be out in it," said Thrift, wrapped up in a thick coat. "We'll be safe. When the boss man says that's it, it's too slippery, we'll just come back here and wait."

At a nearby Publix grocery story, shoppers had cleaned out three shelves of bottled water, and all the boxed fire logs were gone. The milk cabinet had big gaps where rows of gallon jugs were missing.

Forecasters said the Hampton Roads area of Virginia could see a foot of snow. Schools and businesses planned to close early, with the storm expected to further clog an already-busy afternoon commute.

In coastal Charleston, it was a balmy 62 degrees Monday. But the approaching weather led the College of Charleston to cancel classes Tuesday. There was a forecast of rain, and sleet in the late afternoon, with the first snow expected Wednesday morning. The city was expecting up to 3 inches of snow and a ½ inch of ice.

Nationwide, nearly 3,000 flights within, into or out of the U.S. had been cancelled Tuesday, according to statistics from the flight tracking service FlightAware. Only a couple of hundred flights are canceled in the U.S. on a typical day.

At the Okefenokee Swamp in far south Georgia, the alligators were slowing down and burrowing into mud to stay warm.

"Their metabolism slows down so they're able to not breathe as often, so they don't have to come to the surface as often," said Susan Heisey, a supervisory ranger at the Okefenokee National Wildlife Refuge. "These alligators have been on this earth a long time and they've made it through."

In North Carolina's Outer Banks, barrier islands that are popular with tourists during the warm seasons, residents braced for as much as 8 inches of snow.

In Louisiana, the heaviest snowfall was likely to be 1 to 3 inches just north of the Baton Rouge metro area.

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Associated Press writers Bruce Smith in Charleston, S.C.; Jay Reeves in Montgomery, Ala.; Ray Henry in Atlanta; Brock Vergakis in Norfolk, Va.; and Janet McConnaughey in New Orleans contributed to this report.