The storms concentrated damage Wichita, Kansas and in Oklahoma, where 21 injuries were reported throughout the state.
The National Weather Service was forecasting more of the same for the area - including Oklahoma City and Tulsa - Monday afternoon and evening, warning of the possibility of tornadoes and baseball-sized hail.
The worst of the damage Sunday appeared to be at a mobile home park located near Shawnee among gently rolling hills, southeast of Oklahoma City.
"It took a dead hit," resident James Hoke said. Emerging from a storm cellar where he sought refuge with his wife and two children, Hoke found that their mobile home had vanished. "Everything is gone."
Forecasters had been warning of bad weather since Wednesday and on Sunday said conditions had ripened for powerful tornadoes. Wall-to-wall broadcasts of storm information spread the word Sunday, leaving Pottawatomie County Sheriff Mike Booth grateful.
"There was a possibility a lot more people could have been injured," Booth said.
Booth said a 79-year-old man was found dead out in the open at the Steelman Estates Mobile Home Park, but the sheriff didn't have details on where he had lived.
Tornadoes were reported Sunday in Iowa, Kansas and Oklahoma as part of a storm system that stretched from Texas to Minnesota.
Emergency officials traversed the neighborhoods struck in Oklahoma in an effort to account for everyone. Keli Cain, a spokeswoman for the Oklahoma Department of Emergency Management, said that, many times in such situations, people who are not found immediately are discovered later to have left the area ahead of the storm.
A storm spotter told the National Weather Service that the tornado left the earth "scoured" at the mobile home park. At the nearby intersection of Interstate 40 and U.S. 177, a half-dozen big trucks were blown over, closing both highways for a time.
Gov. Mary Fallin declared an emergency for 16 Oklahoma counties because of the severe storms and flooding. The declaration lets local governments acquire goods quickly to respond to their residents' needs and puts the state in line for federal help if it becomes necessary.
In Wichita, Kansas, a tornado touched down near Mid-Continent Airport on the city's southwest side shortly before 4 p.m. local time, knocking out power to thousands of homes and businesses but bypassing the most populated areas of Kansas' biggest city. The Wichita tornado was an EF1 - the strength of tornado on the enhanced Fujita scale - with winds of 110 mph (177 kph), according to the weather service.
Golf ball-sized hail slammed homes in the area.
In Oklahoma, aerial television news footage showed homes with significant damage northeast of Oklahoma City. Some outbuildings appeared to have been leveled, and some homes' roofs or walls had been knocked down.
In Katie Leathers' backyard in Edmond, the family's trampoline was tossed through a section of fence and a giant tree uprooted.
"I saw all the trees waving, and that's when I grabbed everyone and got into two closets," Leathers said. "All these trees just snapped."