An elderly man died when a tornado picked up a parked car and smashed it into his house in Ohio, officials say.
The 81-year-old of Celina, Ohio, was killed as he slept by one of 53 suspected twisters that pulverised eight US states on Monday.
The damage was so severe in Ohio that authorities reportedly used snow plough trucks to clear away debris.
Ohio saw nine suspected tornadoes while 14 hit neighbouring Indiana, according to forecasters.
Also on Monday, there were 11 apparent twisters in Colorado, four in Illinois, five in Nebraska, six in Iowa and three in Minnesota.
There was even one as far out west in the country as Idaho, according to the National Oceanic and Atmospheric Administration’s Storm Prediction Center.
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The National Weather Service (NWS) issued tornado watches for parts of New Jersey, Ohio, Pennsylvania and West Virginia on Tuesday.
The man killed in Celina, a town 65 miles (105km) north of Dayton, was named as Melvin Dale Hanna.
Seven people were injured in Celina, and three were in a serious condition, Mercer County Emergency Management Agency Director Mike Robbins told the BBC.
More than 40 people in the the Dayton, Ohio, area were being treated in hospitals for storm-related injuries, according to the Dayton Daily News.
“Our community has been tested before and we have always risen above it,” Dayton, Ohio, Mayor Nan Whaley told a Tuesday morning press conference.
“I have no doubt we will do so again today and in the coming week.”
The NWS said a “large and dangerous tornado” was on the ground on Monday night near the city of Trotwood, which is part of Greater Dayton.
More than 60,000 homes and businesses in Ohio were without power on Monday morning, according to the PowerOutage.
A boil-water advisory was issued in the Dayton area because local water plants and pump stations were among those that lost power.
Beavercreek, a Dayton suburb, issued an emergency declaration.
“Areas are being closed,” the police department wrote on Facebook, “many gas leaks also reported.
“Please stay out for your safety and others. We are still in the search and rescue mode.”
Montgomery County, which includes Dayton, said Red Cross shelters had been set up across the region, offering water and food.
“We are focused on supporting life saving measures, such as shutting down gas lines or locating people who are trapped by debris,” it wrote on Twitter.
Firefighter Nicholas Hosford told ABC News that no community can ever be “fully prepared for this type of devastation”.
“We have homes flattened, entire apartment complexes destroyed, businesses throughout our community where walls have collapsed,” he said.
Blake Gifford, who sheltered in Dayton’s New Life Worship Center bathroom with 25 other people as the winds knocked down the church steeple, told WKEF-TV: “It was the scariest 15 seconds of my life.”
“I was praying, asking God to keep us safe,” Mr Gifford said. “We’re lucky, we’re lucky to be here.”
Tornados were also confirmed in Pendleton, Indiana, about 100 miles (160km) west of Dayton.
More thunderstorms were forecast for Tuesday, the Madison County Emergency Management Agency tweeted.
A spokesman for the agency told the Indianapolis Star newspaper that trees were down “on every street” in the city.
Indiana officials declared the town “closed off to motorists” and requested that residents shelter in place.
The US Southern Plains and Midwest regions have been hit by several tornadoes, as well as severe rains and flooding in recent days.
Two people were killed in Oklahoma over the weekend when a tornado tore through a hotel and mobile home park in the city of El Reno.
The Office of the Chief Medical Examiner in Oklahoma identified the two victims as Timothy Solis, 53, and Bridget Brockwell, 47, according to the Associated Press news agency.
Both died as a result of blunt force injuries.
The mayor of Tulsa, Oklahoma warned on Monday that more rain could lead to the “the worst flood in our history”.
Residents near the Arkansas River – which is forecast to crest at a record high on Tuesday – have already been evacuating, after being warned that levees could fail.
Hundreds of homes in Sand Springs, Oklahoma have already flooded.
Every single county in the state is currently under a state of emergency due to “flooding, severe storms, tornadoes, and straight-line winds that began in April”, according to state emergency officials.