At least 14 people were killed as spring-like storms mixed with unseasonably warm weather and spawned rare Christmastime tornadoes in the southern U.S., officials said Thursday.

Emergency officials blamed the severe weather for injuring scores of others and destroying dozens of cars, homes and businesses.

The threat of tornadoes eased as the line of storms moved east Thursday and brought heavy rain and thunderstorms to Atlanta and the Carolinas. In the communities worst-hit by Wednesday's tornadoes, search parties hunted for missing people and volunteers helped clear debris on a day often reserved for gift wrapping and last-minute shopping.

Bobby Watkins and his wife huddled beneath their old oak dining table for shelter as storm winds roaring outside their Mississippi home tossed a barn onto their truck outside, tore the steeple off a nearby church and reduced a neighbouring building to rubble.

"Santa brought us a good one, didn't he?" Watkins said Thursday as the couple took a Christmas Eve stroll amid the destruction in rural Benton County, Miss. "I may have lost some stuff, but I got my life."

Widespread flooding

The torrential storms dumped more than 25 centimetres of rain across parts of southeast Alabama, causing widespread flooding Thursday. In Chambers County, emergency officials said two roads had collapsed because of rain, causing natural gas leaks from ruptured lines.

In Linden, Tenn., Chris Shupiery wore a Santa hat as he cut fallen trees with a chain saw not far from a home in which two people died in the storm.

"I figured I'd come down here with my hat," Shupiery said. "I've been wearing it for Christmas, and this was just the right thing to do, come help a family in need. Suit up, try to cheer people up, and try to make them feel a little better with Christmas coming around."

Severe Weather

A woman makes her way to what used to be her bedroom in Holly Springs, Miss., as she and others try to recover what they can from Wednesday's severe storm system. (Thomas Wells/Northeast Mississippi Daily Journal via Associated Press)

From Alabama to New York, much of the country felt unusually warm temperatures of more than 20 C on Christmas Eve, and thousands were without power from Mississippi to Michigan.

The storms killed at least six in Mississippi, including a seven-year-old boy who died when the storm picked up and tossed the car he was in, officials said. Three were killed in Tennessee and one in Arkansas.

Mississippi Emergency Management Agency spokesman Greg Flynn said the state had at least 40 injuries, some serious.

Flight delays

The threat of severe weather just before Christmas is unusual, but not unprecedented, said Greg Carbin, a meteorologist at the national Storm Prediction Center. Exactly a year ago, twisters hit southeast Mississippi, killing five people and injuring dozens of others.

The storms fall on some of the busiest travel days of the year and the severe weather played havoc with travel schedules.

FlightAware, a website that tracks airline flights, showed 550 flights had been canceled countrywide with 4,276 delays by midday.

Atlanta had the largest percentage of delays, according to the site, but many flights also were late in New York and Washington, D.C.