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Alberta Harris points to the room of her Mississippi neighbour's home where she and others helped rescue a bed-ridden man after a tornado struck on Saturday. ((Brian Albert Broom/Associated Press))

Ten people, including three children, died Saturday and dozens were injured as tornadoes tore across a rural swath of the U.S. southeast, crushing buildings and ripping up power lines.

"It's devastating. All of the buildings up in this area have had the roof torn off," said McArthur Straughter, the mayor of Yazoo City, Miss. He estimated up to 20 buildings had been heavily damaged.

Mississippi Gov. Haley Barbour said there was "utter obliteration" in parts of Yazoo County, an area known for cotton, catfish, blues music and picturesque hills rising abruptly from the flat Mississippi Delta.

Power lines and trees were down, blocking roads, Straughter said by telephone as sirens wailed in the background. Emergency crews ferrying injured people to hospital had to drive ATVs to navigate debris-laden streets.

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The tornado ripped through Lauderdale County, Miss., on Saturday, damaging the Green Grove Missionary Baptist Church. ((Paula Merritt/Associated Press))

The 1.2-kilometre-wide twister that hit Mississippi touched down Saturday and roared through at least three counties.

In a notable survival story, a Yazoo City man told local TV news he had been painting inside the Hillcrest Baptist church when he saw the wind storm approaching and dove under the altar. The tornado flattened the building, but the man was unharmed.

Other tornadoes caused injuries in Louisiana, Arkansas and Alabama.

The severe weather forced the postponement of a NASCAR auto race in Talladega, Ala., and halted cleanup work at the site of an offshore oil rig that exploded Tuesday in the Gulf of Mexico about 80 kilometres from the Louisiana coast.

Yazoo City is about 370 kilometres north of New Orleans and was hit by Hurricane Katrina in 2005 after it made landfall.

With files from The Associated Press