A tornado killed multiple people in a small Iowa town as powerful storms swept through the Midwest.

Homes and businesses in Greenfield were destroyed, cars smashed and debris strewn across the landscape.

Iowa police confirmed the fatalities at a news briefing on Tuesday night, but were unable to say how many.

Nebraska, Illinois and Wisconsin were also hit by tornados, heavy rain and power cuts.

Video footage showing the devastation across Iowa depicted flattened buildings, overturned cars and broken wind turbines.

Greenfield, a town of 2,000 people about 55 miles from Des Moines, endured the deadliest tornado of all.

Mary Long rode out the storm inside her Greenfield business and told the Associated Press: “I could hear this roaring, like the proverbial freight train, and then it was just done."

Ms Long's business was not severely damaged but she said other parts of town were not as lucky.

The town's hospital was among the buildings damaged, forcing the dozen people who were injured to go elsewhere.

A "good portion" of Greenfield is devastated, Iowa State Patrol Sgt Alex Dinkla told reporters on Tuesday night.

The death toll was unknown, he said, adding: “We’re still counting at this time.”

Everyone who lives in the town seems to be accounted for, he said.

Iowa Governor Kim Reynolds said she will visit Greenfield on Wednesday morning to assess the damage.

“It was just a few weeks ago that tornadoes hit several other Iowa communities, and it’s hard to believe that it’s happened again," Ms Reynolds said in a statement.