A dozen tornadoes have touched down in Oklahoma, threatening the homes of six million people.
Twisters, hail and severe weather have caused damage to homes and structures, with the threat of more stretching across a 400-mile (644km) area.
Flash flooding from torrential rains with the storms are some of the biggest threats.
More than a dozen sightings of tornadoes were reported in Oklahoma, Kansas, Texas and Missouri but mostly in sparsely populated area.
Oklahoma residents were nervous as it has been six years since a tornado in Moore which killed 24 people.
Glynadee Edwards, the Greer County emergency management director, said some homes had roof damage, and the high school’s agriculture barn was destroyed, but the livestock survived.
She said: “The pigs are walking around wondering what happened to their house.”
A home in Lucien, north Oklahoma, was severely damaged and a barn was destroyed.
One storm spawned two tornadoes in Norman.
A severe thunderstorm threat remains in Missouri and northern Arkansas.
A statement from governor Kevin Stitt issued on Monday said: “Multiple rounds of storms are expected to move through the state today into Tuesday. The public is urged to be weather aware throughout the day and overnight and have multiple ways to receive weather alerts.
“Individuals and families should review their preparedness plans, refill emergency kits, and clean out their safe refuge areas, including safe rooms, basements, or the lowest level interior room of their homes.
“Be prepared to take your emergency precautions before dangerous conditions threaten.
“Flash flooding will be an additional concern, and drivers are reminded not to drive around barricades or into flooded roadways.”
Some schools had cancelled classes when the forecasts predicted hail and wind gusts of up to 80mph.
Some flights were cancelled at Will Rogers World Airport in Oklahoma City.
However, the weather is not been as severe as first thought. There have been no injuries reported.
Source: SKY NEWS