More than 100 tornadoes had been reported across the region by daybreak, according to the National Weather Service. Although the storm system was weakening as it crawled into Arkansas and Missouri and additional tornadoes were unlikely, forecasters warned that strong thunderstorms were expected as far east as Michigan.
Five people were killed and more than two dozen were injured in Oklahoma, where a suspected tornado ripped through a mobile home park in Woodward, about 140 miles northwest of Oklahoma City. Streets in the 12,000-resident town were left dotted with mangled vehicles, toppled power lines and leveled buildings.
Retired firefighter Marty Logan said he spotted the tornado when it knocked down power lines, causing flashes of light, and saw a radio tower's blinking lights go black shortly after midnight. He later saw a man emerge from a twisted, wrecked sport utility vehicle that had been tossed along the side of the road.
"The guy had blood coming down his face," Logan said, adding that he saw people walking down the street covered in blood when he went to a hard-hit neighborhood. "It was scary, because I knew it was after midnight and a lot of people were in bed."
Search teams were scouring rubble for trapped and injured as the sun came up.
"They're still going door to door and in some cases, there are piles of rubble and they are having to sift through the rubble," said Michelann Ooten, an Oklahoma emergency management official.
In the tiny western Iowa town of Thurman, piles of toppled trees lined the streets in front of homes where missing walls and roofs exposed soaked living rooms. Longtime resident Ted Stafford recalled feeling his home shake, then hearing three windows shatter as the storm hit. He said he was amazed that no one in town was seriously injured.
"We're all OK, fortunately. Nobody's hurt. We can fuel this recovery with beans and coffee," the 54-year-old said while standing on the broken concrete of what had been his home's new basement foundation. "I've seen storms in Thurman. I've lived here my whole life. And this is by far the worst I've ever seen."
The storms were part of an exceptionally strong system that the Storm Prediction Center in Norman, Okla., which specializes in tornado forecasting, had warned about for days. The center took the unusual step of warning people more than 24 hours in advance of a possible "high-end, life-threatening event." Forecasters had worried the storms would hit overnight, when people are less likely to hear warning sirens and pay attention to weather reports.
At the storm's height, tornadoes popped up faster than they could be tallied. The center's spokesman, Chris Vaccaro, said the weather service had received at least 120 reports of tornadoes by dawn Sunday.
He warned the threat wasn't over for those across several states in the nation's interior. Forecasters predicted the possibility for storms Sunday in a swath that stretched from southern Texas to northern Michigan.
The outbreak began when tornado sirens went off before dawn in Oklahoma City on Saturday. As the wide-ranging storm system lumbered across the nation, storms also were reported in Kansas, Iowa and Nebraska. Lightning, large hail and heavy downpours accompanied the system.
Woodward Mayor Roscoe Hill said warning sirens sounded loudly on Saturday afternoon when storms rumbled through but he didn't hear the sirens go off for Sunday's tornado. He said the tornado struck a mixed area of residences and businesses and possibly damaged a mobile home park.
"We had a little tornado earlier ... and they blew all the sirens. When this one came in, our sirens weren't working," Hill said. But he later said in televised reports that some reported hearing sirens closer to the tornado's track though he didn't from his home about 10 blocks away.
The American Red Cross summoned volunteers to drive relief trucks from Oklahoma City to aid the rescue crews in and around Woodward he said were pressed to the limit by the immediate disaster response.
"They're in chaos mode," said Rusty Surette, a regional communications director for the American Red Cross in Oklahoma City, speaking of authorities in Woodward.
He said trucks with cots, food, water and medical and hygiene supplies would head to the area, where a shelter was established in a church for those rendered homeless. More than 8,000 people were without power.
Dave Wallace, chief executive officer of Woodward Regional Hospital, said 29 people, five of them in critical condition, were brought to the hospital for treatment of injuries ranging fractures and serious injuries to cuts and bruises. Three patients have been transferred to other hospitals and four were admitted, he added.
"We transferred them to a hospital with a higher level of care," Wallace said. "We're not a trauma center."
Numerous tornadoes were reported in Kansas, though mostly in rural parts of the western and central sections of the state. A reported tornado in Wichita that struck late Saturday night caused damage at McConnell Air Force Base and the Spirit AeroSystems and Boeing plants. A mobile home park was heavily damaged in the city, although no injuries or deaths were reported.
The county where Wichita is located was declared a state of disaster and said preliminary estimates suggest damages could be as high as $283 million.
Yvonne Tucker rushed to a shelter with about 60 of her neighbors at Pinaire Mobile Home Park. She said people were crying and screaming, and the shelter's lights went out when the twister hit. When they came back outside, they found several homes destroyed, including Tucker's.
"I didn't think it was that bad until I walked down my street and everything is gone," said Tucker, 49. "I don't know what to do. I don't know where to go. I've seen it on TV, but when it happens to you it is unreal.
"I just feel lost."
A hospital in Creston, about 75 miles southwest of Des Moines, suffered roof damage and had some of its windows blown out by the storm, but patients and staff were not hurt. Medical center officials were calling other area hospitals to determine how many beds they had available in case they needed to move patients.
In Nebraska, baseball-sized hail shattered windows and tore siding from houses in and around Petersburg, about 140 miles northwest of Omaha. In southeast Nebraska, an apparent tornado took down barns, large trees and some small rural structures.
Kristin Dean, who was among the Wichita mobile home taking shelter from the storm, said she was shaking as she was being pushed from home in her wheelchair. She was able to grab a bag of her possessions before going into the shelter and that was all she had left. Her home was gone.
"It got still," the 37-year-old woman, who's in a wheelchair after hurting her leg a month ago, recalled of the scene inside the shelter. "Then we heard a wham, things flying. Everybody screamed, huddling together.
"It is devastating, but you know, we are alive."
Hegeman reported from Wichita, Kan. Associated Press reporters Grant Schulte in Thurman, Iowa; Rochelle Hines in Oklahoma City; Timberly Ross in Omaha, Neb.; David Pitt in Osceola, Iowa; and Heather Hollingsworth in Kansas City, Mo. contributed to this report.