One fatality has been brought into Faith Regional Medical Center in Norfolk and at least 15 people have been brought in with critical injuries, said Jacque Genovese, the hospital's director of marketing and public information officer for the weather incident. More of the injured were being brought in, Genovese said.
The Associated Press reported the number of those critically injured was 16.
One large tornado had caused "significant damage" near Stanton, Neb., the Weather Channel reported on its Twitter feed. The National Weather Service reported several homes had been destroyed in Pilger, Neb.
One tweet from PzFeed Top News said the town was "leveled" by a massive tornado.
Brian Davidson, a freelance photojournalist and storm chaser in Pilger, told the Omaha World-Herald that the northern part of the town had been hit by one or two tornadoes. He said every structure he could see for five or six blocks had been damaged. Some injuries may have occurred.
He also saw a car inside a home. "It's very chaotic here right now."
Photos and videos from other storm chasers in the region showed at least two tornadoes spinning across farmland in eastern Nebraska.
Much of eastern Nebraska, northern Iowa and southern Minnesota remained under a tornado watch as of late afternoon. The entire region was under a "moderate" risk of severe storms through the rest of the day, the Storm Prediction Center reported, with violent tornadoes possible.
Additional storms will roll through Omaha, Neb., Monday, home of the College World Series, AccuWeather predicted.