A tornado cut a swath about 13 miles long in southern Illinois' St. Clair County on Monday, the National Weather Service confirmed.
The tornado first touched down near O'Fallon, then traveled southeast. The thunderstorms also produced damaging straight-line winds up to 65 mph, damaging several homes, uprooting trees and toppling power lines.
About 3,300 Ameren customers remained without power Tuesday.
The high winds and hail also hit Perry, Franklin and Williamson counties near the Kentucky border.
Two minor storm-related injuries were reported in DuQuoin, in Perry County.