Dozens of tornadoes sliced across southern US states ripping apart homes and shopping malls, killing at least 52 people and injuring hundreds more, officials and US media said.
Twenty-eight people were killed in Tennessee, 13 in Arkansas, and seven in Kentucky, officials in the three states said.
US media reported hundreds injured, and CNN said four people were killed in Alabama. Local authorities were not immediately available to confirm the toll.
"I've seen tornadoes on the ground and I've seen them in the air, but this was different. This one was wide, a massive funnel," Jean Byrd of Mason, Tennesee, a town of just over 1000 residents, told AFP.
With a sigh of relief, Byrd added: "It touched down just after it passed our house. We were lucky."
President George W. Bush offered prayers and disaster relief. "Prayers can help, and so can the government," Bush said in Washington. "I do want the people in those states that the American people are standing with them."
More than 50 tornadoes touched down as a series of rare winter thunderstorms rolled through the region late Tuesday and early Wednesday.
In Tennessee, twisters knocked down a police radio tower, punched holes in a shopping mall, damaged a hangar at the Memphis airport, and ravaged a university campus, emergency officials said.
Overall, 149 people were injured in the state, said Julie Oaks of the Tennessee Emergency Management Agency.
"That'll probably be going up through out the day. We have widespread damage across the state," she said.
Students at Union University in Jackson, Tennessee, heroically rescued classmates trapped in the dead of night after two campus dormitories collapsed, university president David Dockery said.
Fifty-one students were treated in hospital, including some with extensive injuries. But no one was killed, even though 1200 students were on campus at the time.
"It's an amazing thing," Dockery told a press conference.
The campus has already been rebuilt once after a 2002 tornado caused $3.2 million in damage. Now, "we are estimating that the damage is at least 15 times what that was at that time," he said.
Elsewhere in Tennessee, the Red Cross moved 50 people trapped at a retirement center in Madison County to a shelter, officials said.
But a huge fire that blazed overnight at a storm-damaged gas pumping station northeast of Nashville, part of a 6760km line pumping gas through four southern states, had burned itself out.
In neighboring Kentucky, three people were killed in a trailer park in Muhlenberg County, and four others died in Allen County, Buddy Rogers of the Kentucky Division of Emergency Management told AFP.
In Arkansas at least 13 people were killed Tuesday by tornadoes that tore through the state, injuring dozens and destroying houses and businesses in a number of towns.
Four tornadoes were confirmed by the National Weather Service, and another five were reported but unconfirmed. More here.