A strong storm system rolled across the nation's midsection on Monday with tornadoes and high winds that smashed several buildings, while snow was blamed for a massive traffic pileup that killed one person.

In southwest Missouri, three people were treated for minor injuries after a possible tornado flattened an antique store and gutted a gas station in Buffalo.

Terry Lane, emergency management director for Missouri's Dallas County, said the damage may have been caused by a sudden "downburst" from the thunderstorm.

"There was no warning. We had nothing on radar" to indicate a funnel cloud, Lane said.

Strong winds collapsed a convenience store; many buildings were damaged with roofs ripped up and windows blown out, and trees and power lines were toppled along a narrow path through Neosho, about 90 miles southwest of Buffalo.

Emergency officials said a tornado touched down briefly in rural Lawrence County. It damaged a large barn and some utility poles south of Miller.

In Oklahoma, residents in northern Oklahoma County were cleaning up from a twister that touched down before dawn and tore a roof off a house and damaged other buildings. No injuries were reported.

National Weather Service meteorologist Rick Smith said an investigation showed the damage was caused by a short-lived tornado.

Several roads in northwest Oklahoma County were closed by high water. Pawhuska in far northern Oklahoma received 3.88 inches of rain.

In Colorado, at least one person died and more than a dozen others were injured in a snowy pileup that involved as many as 75 vehicles along Interstate 70 near Vail Pass, shutting down the main east-west route, State Trooper Gilbert Sullivan said.

Heavy snow also fell across parts of Minnesota and Wisconsin. St. Paul, Minn., got almost 8 inches.

Rain showers moving across Illinois canceled or delayed hundreds of flights.

More than 400 flights at O'Hare International Airport, one of the nation's busiest, had been canceled, said Chicago Department of Aviation spokesman Gregg Cunningham.

The downpours also brought flood warnings to Illinois. The Weather Service issued a warning for the Fox River at Algonquin and said moderate flooding occurred at the Rock River in Rockton.