AFP

CHICAGO RESIDENTS of stricken towns across six Midwestern and southern US states picked through the debris on Thursday in the aftermath of a string of destructive tornadoes that left 13 people dead.

The last known fatality was a 53-year-old Kansas man who died in hospital of injuries suffered when his home collapsed on top of him on Tuesday in the town of Harveyville, local media reported.

Homes were smashed to bits, cars tossed into lakes, trees uprooted and shops reduced to rubble in towns from Nebraska to Kentucky as the powerful system whipped up strong winds, hail and ominous funnel clouds.

The town of Harrisburg, Illinois was the hardest hit after it was ripped apart by a deadly twister that stayed on the ground for miles, striking while most were still sleeping early on Wednesday morning.

At least six people were killed and more than 100 injured in Harrisburg, a southern Illinois town with a population of 9,000.

The monster twister packed winds up to 170 miles (270 kilometers) per hour and damaged or destroyed up to 300 homes and 25 businesses, smashing a strip mall to bits and tearing a wall off the local hospital.

Harrisburg mayor Eric Gregg called Wednesday’s destruction and loss of life “devastating” and vowed to provide care for those who were hurt and displaced.

President Barack Obama called the governors of Missouri, Illinois, Tennessee, Kentucky, Indiana and Kansas to express his condolences and assure them that federal help was on hand.

“Our thoughts and prayers go out to the victims of these terrible storms, to the families of those who lost loved ones,” White House spokesman Jay Carney, traveling with the president in New Hampshire, told reporters.

The National Weather Service has received 30 reports of tornadoes in six states since the storm began Tuesday, battering Nebraska and Kansas before rolling eastward to Missouri, Illinois, Indiana and Kentucky.

Severe thunderstorms pounded several southern states on Wednesday before the bad weather pummelled toward the eastern seaboard.

Missouri governor Jay Nixon called in the national guard to help with the cleanup after at least three people were killed by tornadoes which ripped across the southern portion of the state.