DALLAS (Reuters) - Storms hit southern and central U.S. states over the Christmas holiday, unleashing floods and tornadoes that killed at least 41 people, flattened buildings and snarled transportation for millions during a busy travel time.

Traffic goes across the bridge on Alabama hwy 87 at the Pea River in Elba, Alabama, December 26, 2015. REUTERS/Marvin Gentry

At least 11 people were killed in the Dallas area over the weekend by tornadoes, including one packing winds of up to 200 miles per hour (322 km per hour). The twister hit the city of Garland, killing eight people and blowing vehicles off highways.

“A tornado of that strength is very rare in a metropolitan area,” National Weather Service meteorologist Matt Bishop said in a telephone interview. Powerful tornadoes are a staple of spring and summer in central states but occur less frequently in winter, according to U.S. weather data

“It is total devastation,” Garland Police spokesman Lieutenant Pedro Barineau said. “It is a very difficult time to be struck by such a horrible storm the day after Christmas.”

Three other deaths were reported in the Dallas metropolitan area, the United States’ fourth most populous with about 7 million residents. Scores of people were injured in the region, officials said.

Three tornadoes were reported in Arkansas on Sunday, the weather service said, but there were no initial reports of significant injuries or damage. The service has issued tornado watches and warnings for areas in that state, as well as in parts of Texas, Louisiana and Mississippi.

A tornado watch means a storm is likely, while a warning means a storm or storms have been sighted.

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In Illinois and Missouri, flash flooding killed at least 11 people, officials and local media reported on Sunday.

Six adults drowned when they drove their cars into flooded waterways in Missouri’s Pulaski County, said county Sheriff Ron Long.

In neighboring Illinois, Salem-based radio station WJBD reported a family of three adults and two children was driving near the village of Patoka, 85 miles (137 km)east of St. Louis, Missouri, when their car was washed away by floodwaters.

The storms came on the heels of tornadoes that hit two days before Christmas, killing at least 18 people, including 10 in Mississippi.

In Alabama’s Coffee County, the body of a man who went missing during those storms was found on Sunday, officials told local media.

In Texas, Governor Greg Abbott said his office had declared Dallas County and three nearby counties disaster areas. He also warned people to be wary of snow in western parts of the state and rivers spilling their banks in other places.

“If you do not need to be on the road, please stay off the road,” he said at a news conference.

The weather service issued severe weather advisories for large parts of the central United States, including a blizzard warning for parts of New Mexico, Texas, Oklahoma and Kansas and a flash flood watch stretching from Texas to Indiana.

New Mexico Governor Susana Martinez declared a state of emergency for the entire state due to a winter storm expected to dump up to 2 feet of snow in eastern parts of the state.

The bad weather forced the cancellation of nearly 1,300 flights in the nation as of 4:30 p.m. EST on Sunday, according to tracking service FlightAware.com. About half of the canceled flights were in Dallas, a major U.S. flight hub.