Authorities said four people were injured from the tornado as well. The tornado swept through central Iowa, damaging buildings and knocking down trees and power lines, authorities said. Officials didn't identify those killed or release details about what had happened.
In a Tweet, the National Weather Service of Des Moines said "initial interrogation of photos and videos from around Winterset suggests at least EF3 tornado damage occurred late Saturday afternoon," adding that "NWS survey teams will be out Sunday to thoroughly investigate the damage and further assess a potential rating."
Thunderstorms that spawned tornadoes moved through much of Iowa for hours Saturday with some of the most intense damage in the small Madison County community of Winterset. Storms also caused damage in the Des Moines suburb of Norwalk and areas just east of Des Moines.
Officials reported a number of homes were damaged, roads were blocked by downed lines and tree branches were shredded by the strong winds. Photos tweeted on social media showed downed trees, debris and damaged roofs and vehicles.
A severe thunderstorm warning was issued for Cook, DuPage, Lake, and Will counties until 11:45 p.m. Saturday. Warnings for de Kalb, Boone, Kane, McHenry and Kendall counties were canceled.
Winds up to 60 mph were reported in Grove Village at 11:16 p.m.
The Associated Press contributed to this report.