At least 19 people were killed Saturday and many injured as tornadoes ploughed across the mid-west and south-east of the United States, dpa reported.
The numbers injured and the extent of the damage to property and infrastructure was still unclear, according to reports from US broadcaster ABC.
Numerous people were reported missing Sunday, while rescue and fire services were searching the many ruined buildings in the most remote areas for people who might have become trapped.
The south-east of the US was under threat of more storms Sunday. The states of Oklahoma, Arkansas and Missouri have been worst hit by the storms that have been raging since Thursday.
In Oklahoma alone, five tornadoes have been registered. At least 12 people were killed in Missouri, the majority of them near Seneca close to the Oklahoma border, where in the small town of Picher seven others died, including a young child.