US authorities say at least seven people, including two children, died in Des Moines town and Lucas County.

EF-3 storms typically have winds in excess of 130 mph.
EF-3 storms typically have winds in excess of 130 mph. (AP)

At least seven people have been killed, including two children, when a tornado swept through central Iowa, damaging buildings and knocking down trees and power lines.

Emergency management officials in Madison County said four were injured and six people were killed on Saturday when the tornado touched down in the area southwest of Des Moines near the town of Winterset. 

Among those killed were two children under the age of five and four adults.

In Lucas County, officials confirmed one death and multiple reported injuries.

Thunderstorms that spawned tornadoes moved through much of Iowa from the afternoon until Saturday night with storms also causing damage in the Des Moines suburb of Norwalk, areas just east of Des Moines and other areas of eastern Iowa.

Officials reported a number of homes were damaged, roads were blocked by downed lines and tree branches were shredded by the strong winds. 

At one point, power outages affected about 10,000 in the Des Moines area.

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'Unusual but not unheard'

The National Weather Service in Des Moines tweeted early on Sunday that there were at least three thunderstorms producing tornadoes, but it's “unknown at this time how many tornadoes occurred.”

Meteorologist Alex Krull said it's unusual but not unheard of to have serious storms like this in March in the Midwest. He said they are more common in April and May.

Iowa Governor Kim Reynolds issued a disaster proclamation for Madison County, which allows state resources to be used to assist with response and recovery efforts.

“Our hearts go out to all those affected by the deadly storms that tore through our state today,” Reynolds said. “Our hearts ache during this time, but I know Iowans will step up and come together to help in this time of need—they already are.”

The National Weather Service in Des Moines tweeted on Saturday that initial photos and videos from the damage around the community of Winterset suggested it was at least an EF-3 tornado, capable of causing severe damage, on the Enhanced Fujita scale.

EF-3 storms typically have winds in excess of 130 mph.

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Source: TRTWorld and agencies