At least 49 tornadoes churned a trail of destruction through five states in the South and Midwest, killing at least seven people and injuring dozens. National Guardsmen in Arkansas helped search for people and clean up damage Wednesday.

The same storm system left three people dead in road accidents in the season's first major snowfall. The storms were followed Wednesday by a blast of cold weather that forced school closings in Nebraska and Minnesota.The twisters took their worst toll in Arkansas, where six people were killed and many others injured. Tornadoes damaged buildings and overturned cars.

"I can't even tell what street I'm on because the trees are uprooted," said Police Chief Darnell Scott of the central Arkansas town of Lonoke. "Damage is so bad. I think we were very lucky it wasn't more tragic than it was."

National Guardsmen went house to house in the Scott area of Pulaski County, where a couple and their 1-year-old son were killed, said sheriff's spokeswoman Sherry Rainey. "They're trying to account for everyone. We're also checking fields, looking for people who might be injured."

Tornadoes also struck Missouri, Kansas, Illinois and Iowa, while in Oklahoma high winds caused damage and fanned the flames of a cotton fire that destroyed 29 homes and businesses and injured 18 people in Altus.

One person died in Missouri when a tornado threw a trailer home into the air, authorities said. A woman in Illinois was electrocuted by a power line downed by high wind.

The twisters and their accompanying thunderstorms were created by an intense area of low pressure over the upper Mississippi Valley and a cold front trailing south from the low.

The same low pressure system produced up to a foot of snow over most of Colorado and western Kansas on Tuesday, and the snow moved Wednesday into the eastern Dakotas, Minnesota, Iowa and Nebraska. It closed schools in Colorado and caused three traffic fatalities there.

In Arkansas, as many as 10 tornadoes touched down Tuesday night, toppling trees, downing power lines and crumpling mobile homes, houses and businesses. Two people were killed on Interstate 40 near Lonoke when high winds overturned their vehicle.

Three other people were killed when a tornado ripped through the town of Scott in west-central Arkansas, and a man injured when a twister struck north-central Arkansas later died at a hospital, authorities said.

More than a half-dozen people were treated at a Clarksville, Ark., hospital for injuries from high winds, Johnson County Sheriff Eddie King said.

In southwest Missouri, officials searched beneath overturned trailers for victims of a tornado that hit Butterfield. The Barry County Sheriff's Department said a 69-year-old woman died when the twister flung her double-wide mobile home into the air.

Deputy Sheriff Mike Cooper said 24 houses and trailers were damaged or destroyed, leaving 15 people injured, 11 requiring hospitalization.

In Topeka, Kan., a tornado descended without warning, crashing into Topeka West High School shortly before 2 p.m.

"Everyone's ears started popping and the teacher told us to get down," said student Jennifer Stanley. "All the windows started popping out."

Six students suffered minor cuts from broken glass, said Superintendent Gary Livingston.

The tornado skipped through the city, causing more than $3.5 million in damage as it battered about 50 homes and destroyed as many as 20 others, Mayor Doug Wright said. About 15 businesses were damaged or destroyed.