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.

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.