'If anything, we were expecting we could get some large hail, if strong storms developed'.
The storm knocked out power and telephone service at city hall, officials said. She did not know how serious those patients' injuries were.
There were 27 reports of tornadoes in the state Thursday, CNN meteorologist Brandon Miller said.
Some funnel clouds appeared as a result of the thunderstorm as it traveled north of Des Moines near Bondurant.
She her a storm siren and her mother texted her to seek shelter, so she and her son, Fredy Jr., rushed to the basement.
In Pella, some workers at Vermeer Manufacturing were taken to a hospital, according to police.
Storm damage was also reported in the communities of Marshalltown, where a video circulated of a building's steeple being torn off by a tornado, and Pella.
McFarland Clinic posted on Facebook the Marshalltown Main Street building was damaged, but there are no reports of injuries to patients or staff in the building.
The storm carried east of Des Moines past Altoona, Prairie City and Colfax.
The city had activated its tornado siren and most staff were in underground shelters when the storm hit, but huge sheets of metal were left scattered through a vehicle park, ripping a hole in the side of a building, overturning cars and piling them onto others.
Iowa State Rep. Mark Smith, who lives in Marshalltown, told KCCI-TV that the area likely will be declared a disaster area. Smith said his house and neighbourhood were not damaged, but much of downtown and surrounding homes have been.
The exact number of tornadoes and their strength will be determined after further analysis.
Trees crashed onto roads, cars were flipped, houses left without roofs and the clock tower of a historic courthouse tumbled 50m to the ground. They all were released after being treated for their minor injuries, Rhamy said.
Vermeer spokeswoman Liz Sporrer told the Des Moines Register that the business was hosting visitors for a special event when the tornado struck.
Other towns hit by this system were Bondurant and Pella.
He said emergency responders are attempting to get inside the damaged building to see if anyone is trapped there.