Tornadoes touched down in Hazelwood, Florissant and Alton, Mo., causing extensive damage across the area, KTVI-TV, St. Louis, reported.
The violent spring storm snapped power lines and closed interstates along the affected area.
More than 2 feet of snow fell in some places in Wyoming Tuesday into Wednesday, and blizzard conditions were reported for communities from Colorado to South Dakota, AccuWeather.com reported.
During a 2-hour window, temperatures plummeted 26 degrees in Denver to 42 degrees Tuesday evening. About this time, wind gusts reached their peak of 55 mph.
AccuWeather.com reported a half-inch of freezing rain in Hutchinson, Kan., accumulating on trees and power lines. Freezing rain also was reported near Wichita and Concordia.
In several states, officials reported more than a foot of snow in some areas, including 18 to 29 inches in the Lander, Wyo., area. Other 12-inch-plus snowfall amounts include 15 inches in Rapid City, S.D.; 16 inches in Boulder, Colo., and 12 inches in Cheyenne, Wyo.
More than 200 arriving and departing flights in Denver were canceled Tuesday because of the storm, Flightstats.com indicated.
Drifting snow forced all roads in Goshen County, Wyo., to close for a while Tuesday afternoon, local officials said.
In South Dakota, blizzard conditions forced officials to close a portion of Interstate 90 from Rapid City to Sioux Falls, the Sioux Falls Argus Leader reported.
More than 11,000 homes and businesses in the Sioux Falls area were without power Tuesday night because of the ice storm that slammed the area knocked down power lines and tree branches.
"This is the perfect storm," Sioux Falls Mayor Mike Huether said. "It's wet, there is ice. But there is wind coming, more ice and snow coming. This is going to go on for days."
Schools throughout the area were closed Wednesday.
Part of the Avera McKennan Hospital used emergency generators for about 90 minutes Tuesday, but the facility never lost power completely, Communications Director Lindsey Meyers said.
Parts of Minnesota braced for a possible 15 inches of snow before the storm pushed through.
The first round of precipitation arrived Tuesday night as a wintry mix of rain, freezing rain and sleet across most of southern Minnesota and western Wisconsin, the St. Paul Pioneer Press reported. The National Weather Service said a second, more powerful round of winter weather was expected late Wednesday afternoon into Thursday afternoon.
Snowfall accumulations of 10 to 12 inches, with locally higher amounts approaching 14 or 15 inches, were expected along a line that included the Twin Cities of Minneapolis and St. Paul to Ladysmith, Wis.
Forecasters said more rain and wintry precipitation across the area through the weekend could cause minor rises in rivers and streams.