The two children who died were under the age of five, Madison County Emergency Management Director Diogenes Ayala said.
“This is, I think, the worst anyone has seen in quite a long time,” Ayala said.
The tornado in Madison County, which is southwest of Des Moines, also left one adult with life-threatening injuries and three others hospitalized in serious condition, Ayala said.
“This is a widespread storm,” Ayala said. He estimated there was serious damage to more than two dozen homes.
Two people were injured in nearby Polk County, the sheriff’s office said in a Facebook post.
The severe weather caused “damage to several homes, power lines, and trees,” the sheriff’s office said. First responders were in the area conducting a damage assessment and helping residents.
“Downed powerlines, standing water and debris blocking roadways are creating dangerous travel conditions in this area and we are asking for the public’s assistance by staying clear of the area and allowing these agencies to work unimpeded,” the sheriff’s office cautioned in the post.
Iowa Gov. Kim Reynolds issued a disaster proclamation for Madison County, saying she and her husband are praying for the lives claimed and those injured in the tornado.
The proclamation allows state resources to be used for response and recovery efforts in Madison County, according to the news release. Other counties may be added to the proclamation.
CNN’s Jennifer Feldman, Allison Chinchar and Aya Elamroussi contributed to this report.