The Plains awoke to damage and flooding Thursday after at least 50 tornadoes and baseball-sized hail were reported across a 500-mile stretch spanning four states.
Some of the worst damage was reported near Oklahoma City. A 42-year-old woman drowned in a storm shelter, police said, and at least 12 people were injured after a twister tore through two trailer parks and downed power lines Wednesday.
Gov. Mary Fallin declared an emergency for 12 counties in Oklahoma and planned to tour the damage later Thursday.
Oklahoma City recorded 7.1 inches of rain throughout the day — almost tripling the previous record for rainfall that was set in 1930. Weather Channel lead meteorologist Michael Palmer said this "unprecedented" downpour caused flash floods strong enough in some areas for cars to be partially submerged.
In Kansas, a tornado caused "significant damage" to homes and injured one person in the small community of Jewell, and another damaged buildings near Lincoln, according to the National Weather Service.
Between 10 and 15 homes were damaged in several communities in Nebraska near the Kansas line, The Associated Press reported.
Authorities across the affected area said it was not possible to give a full assessment of the damage until sunrise. No deaths had been reported as of 5 a.m. ET.
"Fifty tornadoes in one day is certainly significant," Palmer said, but added that "luckily most of them came down in rural areas and were relatively short-lived, what we call short-track tornadoes."
There was also more than 80 hail reports across the four states. The hail in Talpa, Texas, was nearly the diameter of a DVD — and smashed car windows and damaged houses.
Palmer said most of the severe weather occurred before midnight local time (1 a.m. ET) and that by daybreak was confined to thunderstorms in southern Oklahoma and northern Texas.
Thursday was likely to be quieter, he said, with the possibility of isolated tornadoes in the afternoon. However, Friday and Saturday were expected to bring more twisters, possibly in the same number and magnitude as Wednesday, Palmer said.
— Alexander Smith
The Associated Press contributed to this report.