It is thought to have been the worst such season for tornadoes since May 3, 1999, when about 50 people died in Oklahoma and Kansas.
"I've seen tornadoes on the ground and I've seen them in the
air, but this was different," one resident of Mason, Tennessee, told AFP.
"This one was wide, a massive funnel."
Tornado watches were in effect on Wednesday morning for parts of
Alabama, Tennessee, Georgia and the western Florida panhandle, the
National Weather Service said.
Assessing damage
Several homes and business in Arkansas
were destroyed [AFP]
In Tennessee, twisters knocked down a police radio tower, crushed the wall of a shopping centre and damaged a hangar at the airport in the largest city, Memphis.

Several people sheltering under a bridge north of the shopping centre were washed into the state's Wolf river, but were rescued, Steve Cole of the Memphis police department said.
Almost 150 people were injured in the state, officials said, and the number is expected to rise.
"That [number] will probably be going up throughout the day," Julie Oaks of the Tennessee Emergency Management Agency, told AFP.
"We have widespread damage across the state."
The same storm then moved to Jackson, Mississippi, and damaged a dormitory at Union University, where eight students were temporarily trapped but escaped serious injury, school officials said.
Four tornadoes were confirmed to have hit Arkansas, where scores of houses and businesses were destroyed in several towns.
Rescue teams searched house to house for trapped people in the state, although downed power lines, trees across roads and power outages
hampered efforts.
George Bush, the US president, said he had called the governors of Alabama, Arkansas, Kentucky, Mississippi and Tennessee to offer assistance.