Dozens of tornadoes and intense thunderstorms swept across the U.S. Midwest on Sunday, unleashing powerful winds that flattened entire neighborhoods, flipping over cars, uprooting trees and leaving at least five people dead.

An elderly man and his sister were killed when a tornado hit their home in the rural community of New Minden in southern Illinois. Two other people were killed in Massac County in far southern Illinois, and one person was killed in the central Illinois community of Washington.

With communications difficult and many roads impassable, it remained unclear how many people were killed or hurt.

The Illinois National Guard said it had dispatched 10 firefighters and three vehicles to Washington, Ill., to assist with immediate search and recovery operations. In the rural community of 16,000, whole blocks of houses were erased from the landscape and one official said the tornado cut a path from one end of town to the other, knocking down power lines, uprooting trees and rupturing gas lines.

"I stepped outside and I heard it coming. My daughter was already in the basement, so I ran downstairs and grabbed her, crouched in the laundry room and all of a sudden I could see daylight up the stairway and my house was gone," said resident Michael Perdun in an interview Sunday afternoon with The Associated Press on his cellphone.

"The whole neighbourhood's gone, the wall of my fireplace is all that is left of my house."

A Washington alderman told Chicago's WBBM Radio that there were "quite a few people hurt" but didn't offer details. The damage, he said, was extensive.

"I went over there immediately after the tornado, walking through the neighbourhoods, and I couldn't even tell what street I was on," said Alderman Tyler Gee. "Just completely flattened — some of the neighbourhoods here in town, hundreds of homes."

Reports of looting in storm's wake

At OSF Saint Francis Medical Center in Peoria, Ill., spokeswoman Amy Paul said 37 patients had been treated, eight with injuries ranging from broken bones to head injuries that were serious enough to be admitted.

Severe Weather Illinois

An overturned car rests on top of tree branches and other rubble northeast of Washington, Ill., after intense thunderstorms spawning tornadoes swept across the U.S. Midwest on Sunday. (David Mercer/Associated Press)

Another hospital, Methodist Medical Center in Peoria, treated more than a dozen people, but officials there said none of them were seriously injured.

Steve Brewer, Methodist Medical Center's chief operating officer, said doctors and other medical professionals were setting up a temporary emergency care centre to treat the injured before transporting them to hospitals.

Others, he said, were dispatched to search through the rubble for survivors.

State Trooper Dustin Pierce told the Associated Press there were reports of looting in Washington as night fell.

The White House issued a statement saying President Barack Obama had been briefed about the damage and was in touch with federal, state and local officials.

Wind, thunderstorms, hail

About 90 minutes after the tornado destroyed homes in Washington, the storm darkened downtown Chicago.

APTOPIX Severe Weather Ind

Sunday's tornado caused major damage to Fire Station No. 6 in Kokomo, Ind., on Sunday. (Kelly Lafferty/Kokomo Tribune/Associated Press)

As the rain and high winds slammed into the area, officials at Soldier Field evacuated the stands and ordered the Bears and Baltimore Ravens off the field. Fans were allowed back to their seats shortly after 2 p.m.

According to the National Weather Services' website, a total of 65 tornadoes struck Sunday, the bulk of them in Illinois. But meteorologist Matt Friedlein said the total might fall because emergency workers, tornado spotters and others often report the same tornado.

Severe thunderstorms packing tornadoes and heavy winds rolled across Indiana Sunday afternoon and evening, injuring several people and causing widespread damage. Gov. Mike Pence said 12 counties reported either tornadoes or storm damage after the initial line of storms had travelled midway across the state. The city police department posted photos on its Twitter account showing buildings with roofs torn off and a destroyed bank branch.

In western Ohio, storms packing strong winds and the potential for tornadoes were starting to roll in on Sunday night. The National Weather Service had issued tornado warnings and watches for several counties along the state's western edge.

Severe storms slammed the eastern part of Missouri, leaving tens of thousands without power and destroying a mobile home. The National Weather Service said the storm tore shingles off of roofs and uprooted trees across parts of St. Louis and St. Louis County.

In Wisconsin, strong winds knocked out power to thousands in the Milwaukee area, damaged buildings and downed trees in Dodge County and sent Sunday churchgoers scrambling into church basements for safety.

High winds and rain slammed into the western part of Michigan. There were no immediate reports of injuries, but Consumers Energy reported thousands of power outages.

The National Weather Service also issued a tornado watch for several counties in southern Kentucky.

'Get ready now'

"We obviously have a very dangerous situation on our hands," Laura Furgione, deputy director of the National Weather Service, told reporters in a conference call earlier Sunday.

'These storms will be moving very fast ... They will be at your location and on to the next location in a matter of minutes. As a result, people cannot wait for visual confirmation of the threat.'- Russell Schneider, Storm Prediction Center.

"Our primary message is this is a dangerous weather system that has the potential to be extremely deadly and destructive ... Get ready now."

The NWS's Storm Prediction Center said the storm was moving dangerously fast, tracking eastward at 97 kilometres per hour, meaning that just looking out at the storm will not be enough to let people know when to take cover.

"These storms will be moving very fast ... They will be at your location and on to the next location in a matter of minutes. As a result, people cannot wait for visual confirmation of the threat," said Russell Schneider of the Storm Prediction Center.

"This is a very dangerous situation ... Approximately 53 million [people] in 10 states are at significant risk for thunderstorms and tornadoes."

'Things can change very quickly'

The potential severity of the storm this late in the season also carries the risk of surprise.

Severe Weather Illinois

Tornado victims sift through an overturned mobile home in Brookport, Ill., on Sunday after a tornado ripped through the small far southern Illinois town. (Stephen Lance Dennee/Associated Press)

"People can fall into complacency because they don't see severe weather and tornadoes, but we do stress that they should keep a vigilant eye on the weather and have a means to hear a tornado warning because things can change very quickly," said Matt Friedlein, a weather service meteorologist.

Friedlein said such strong storms are rare this late in the year because there usually isn't enough heat from the sun to sustain the thunderstorms.

But he said temperatures Sunday were expected to reach around 15 to 20 C — warm enough to help produce severe weather when it coupled with winds, which are typically stronger this time of year than in the summer.

"You don't need temperatures in the 80s and 90s [around 30 C] to produce severe weather [because] the strong winds compensate for the lack of heating," he said.

"That sets the stage for what we call wind shear, which may produce tornadoes."

With files from Reuters