Aerial footage has shown the extent of the tornado damage in the town of Quapaw in the southern US state of Oklahoma.
Several tornadoes touched down as a major storm front moved its way across the continental United States.
One of the two people who has so far been reported dead was in Quapaw, while a second was near the city of Little Rock in the neighbouring state of Arkansas.
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Guillier conceded a "severe defeat" defeat to his supporters as the result came in.
The outage struck Hartfield-Jackson Atlanta International Airport at around 1pm local time, stopping all outgoing flights.
It will be a chilly day for many parts with the highest temperatures, about 10 Celsius (50F) in the far northwest.