CELINA, Ohio – A string of tornadoes unleashing their fury across Ohio and Indiana ripped apart communities and left a wide swath of debris as a two-week wave of severe weather continued its unrelenting assault on the nation's midsection.

Celina firefighter Brian Davis confirmed Tuesday that an 81-year-old man died and seven people were injured when an EF3 tornado roared through just before midnight Monday. As many as 90 homes were damaged.

Celina resident Kylie Post, who said her home was spared, has no basement, so she and her son huddled under a mattress in a bathtub.

"We heard the tornado sirens, and then it got really quiet," Post said. "Next, it sounded almost like a train was near us that lasted for only a few minutes."

Severe weather threatened more than 100 million Americans from Texas to New Jersey, the National Weather Service said.

"Large hail and damaging wind will be the main threats, but a few tornadoes will be possible," the Storm Prediction Center warned.

Late Monday, an area around Dayton, in Ohio's Montgomery County, saw some of the worst damage.

"A large, dangerous tornado touched down last night in northwest Montgomery County," the county said in a statement. "We are focused on supporting life-saving measures, such as shutting down gas lines or locating people who are trapped by debris."

Dayton Fire Chief Jeffrey Payne said no fatalities and a few minor injuries were reported. Considering the amount of property damage, that was "pretty miraculous," he said.

Urban Search and Rescue teams from Columbus and Cincinnati helped first responders pick through rubble in search of survivors, Payne said.

Five miles north of Dayton, Harrison Township Fire Chief Mark Lynch and his crews worked to rescue people trapped in houses and cars.

"Devastation. World War III. It's tough," Lynch said. "It's going to be several years of rebuilding, I'm sure."

More than 50 tornadoes may have touched down in eight states over the Memorial Day weekend, the National Weather Service said. The Midwest has been hammered by scores of tornadoes and heavy storms since mid-May, leaving at least 10 dead and a trail of damage from high winds and flooding.

In the past 30 days, about 500 eyewitness tornado reports were recorded, the Storm Prediction Center said, among the most active periods since records began in 1950.

Late Monday and early Tuesday, the weather service issued a string of tornado watches and warnings from Indiana into Ohio, many of them along the Interstate 70 corridor that cuts through the heart of the two states. The outbreak was so severe the National Weather Service said a tornado near Vandalia cut across the path of the earlier twister.

More than 60,000 homes and businesses were without power Monday in Ohio, the website PowerOutage.US reported. A boil-water advisory was issued, and residents of Dayton and Montgomery County were asked to conserve water after power went out at water plants and pump stations.

Some lanes of Interstate 75 north of Dayton were blocked by debris, and trucks with plows scraped tree branches and rubble to the side of the highway.

In Indiana, scores of homes were damaged or destroyed by storms. The weather service confirmed that a tornado ripped through Pendleton, 35 miles northeast of Indianapolis, damaging more than 70 homes.

Todd Harmeson, a spokesman for the Madison County Emergency Management Agency, said emergency officials went door to door to check on residents. Trees and power lines were down "on every street" in the city, he warned, and power was out across the area.

"Stay inside. Shelter in place if you can," Harmeson said.

Multiple tornadoes ripped through eastern Iowa on Monday, damaging several homes, barns and trees.

Authorities reported a half-dozen tornadoes in the eastern part of the state as a severe weather system moved eastward Monday afternoon. No injuries were reported. The National Weather Service is working on surveying the sites.

"It was about the quickest thing I've ever seen," said Shawn Zweibohmer, who was working on a house he owns outside Charles City on Monday afternoon when the tornado came through. "There was no alert, there was nothing."

The Oklahoma City suburb of El Reno was digging out from an EF3 tornado late Saturday that killed at least two people, destroyed a motel and devastated a mobile home park. Some communities in Oklahoma and Arkansas braced for their worst-ever flooding as the Arkansas River reached record crests in some areas.

Bacon and Rice reported from McLean, Va. Contributing: Ian Richardson, Des Moines Register; Jennie Key and Cheryl Vari, The Cincinnati Enquirer; Kellie Hwang, The Indianapolis Star; The Associated Press