At least eight people have died and dozens were injured after storms triggered tornadoes and flooding across several southern US states, the media reported.
In Texas, two children died after a tree fell on their family car. The parents, who were in the front seats, were not injured.
Deaths were reported across Mississippi, Texas and Louisiana.
Some of the injured could not be rescued for hours due to debris on roadways, according to US media.
Authorities say at least 11 tornadoes touched down in three states before the storm began moving towards the East Coast.
Tornado warnings have been issued for Monday in Ohio, South Carolina and Virginia.
In Pollok, Texas – about 150 miles (240km) southeast from Dallas – two children were killed when their family car was hit by a falling pine tree.
According to Capt Alton Lenderman of the Angelina County Sheriff’s Office, the tree “flattened the car like a pancake”, but the parents, who were riding in the front of the vehicle, were not injured.
The children were aged eight and three.
In Alto, Texas, one person was killed and around two dozen others were injured after a suspected tornado struck a Native American cultural event, Cherokee County officials told the Associated Press.
Franklin, Texas was heavily damaged with nearly 60 buildings destroyed, local authorities say, including around 55 homes and several public buildings.