Eight people are reported to have been killed in Texas after new tornadoes, raising the death toll to 26 in a week of storms in several US states.
Local media said five people in cars were probably blown off a motorway in Garland, near Dallas. Another three bodies were found in nearby towns.
Officials also say Texas and Oklahoma could suffer a "historic blizzard", bringing up to 16in (41cm) of snow.
The storms across the South have been unusually powerful for winter.
Reports from Texas said churches were destroyed, cars mangled and trees toppled across a wide area.
Garland police believed that "winds from a tornado that passed through" the town late on Saturday were the cause of car accidents, Melinda Urbina from the Dallas County Sheriff's office told the BBC.
At least five people were reported dead in the cars.
Ms Urbina said the winds "tossed the cars around", and the vehicles were later found below Interstate 30, about 15 miles (24km) north-east of Dallas.
She also urged local residents to stay off the roads.
(BBC)