Some 27 separate tornadoes have injured 17 people, damaged scores of buildings and overturned vehicles as they tore through the American mid-west state of Iowa.
The unpredicted winds slammed into three separate cities, Marshalltown, Pella and Bondurant, on Thursday.
"It was bad," witness Julie Owen told CNN from Marshalltown. “It's not like the whole town is destroyed, but downtown, a city of this size, it was something else.”
State representative Mark Smith said it was likely parts of the region would be declared a disaster area.
"There are houses with windows out, houses without roofs," he told KCCI-TV. "It's just an absolute mess."
He added that brick walls had collapsed, the cupola of the historic courthouse had tumbled 175ft to the ground, and a hospital was forced to evacuate 40 patients.
Among those hurt were seven people working at an agricultural plant in Pella.
A spokeswoman for the company, Vermeer, said officials were assessing the damage but that all staff injuries had been minor.
Alex Krull, a meteorologist with the National Weather Service in the state capital of Des Moines, said that forecasting models had not predicted the tornadoes. He said they had showed only a slight chance of strong thunderstorms during the day.
"This morning, it didn't look like tornadic supercells were possible," he said. "If anything, we were expecting we could get some large hail, if strong storms developed."
