Residents have woken to the full scale of the devastation left by powerful tornadoes that tore through south-central United States, killing at least 26 people.
And more big twisters were expected as violent thunder and hail storms moved through a large swath of the south, from Texas to Tennessee, forecasters said on Monday.
Tornadoes struck the region on Sunday evening, flipping cars, ripping up homes and uprooting trees. Tens of thousands of people are without power in Alabama, Kentucky and Mississippi.
One of the towns hardest hit, Vilonia, Arkansas, intensified its search for survivors on Monday, after the arrival of daylight allowed a good look at the damage.
Police chief Brad McNew told US television tornado damage had rendered his town unrecognisable.
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"It's houses completely down to the foundations," he told NBC.
Rescuers had worked through the night using searchlights in blacked-out areas as they sifted through mountains of rubble searching for survivors, he said.
The Arkansas Department of Emergency Management said 15 people were killed when the tornadoes touched down, while an official with the Oklahoma Emergency Management Agency said there were at least two tornado victims in the state.
Local media reported another fatality in Iowa.
McNew said there was not yet a final tally of casualties in his town of just 4000 people.
He said, however, the toll would surely have been far worse, if not for emergency sirens that warned citizens of the oncoming twister.
"The storm warnings went out fairly early," he said.
"I went to a tornado shelter myself with my family which was a couple miles away from where we were at. A lot of people in the community were there. And so, it did work," he said.
"If you see the destruction that is here, even though we've lost some lives, there's many lives that was saved because of the storm warnings."
Twisters also devastated large sections of the town of Mayflower, population 2300, just northwest of the Arkansas state capital Little Rock.
The National Weather Service warned of the threat of "a severe weather outbreak" beginning late on Monday, affecting several states, including Mississippi, Tennessee and those on the Central Gulf Coast.
"Numerous tornadoes are expected, some of which could be intense, the NWS said.
"Very large hail and damaging straight line winds are also likely."
