DES MOINES, Iowa (AP) _ Heavy, wet snow and blizzard conditions hit the Plains and Midwest on Thursday, shutting down hundreds of miles of interstate highways as snowplows were pulled off roads in white-out conditions.
Schools closed in several states, and hundreds of flights were canceled. Two people were killed when their car overturned on a slick road in North Dakota, and snowplows were pulled off the roads in Iowa and western Minnesota because of strong wind and heavy snow.
The storm moved into Iowa with rain and sleet but changed to snow around dawn.
The western part of the state was hit with a blizzard that dropped visibility to a quarter-mile or less for at least three hours. By midday, as much as a foot of snow covered the town of Atlantic.
The blizzard also hit eastern Nebraska, with a foot of snow in the Omaha area and up to 15 inches of snow expected in some areas before it dies off Friday.
Pat Sinnott, who owns the Pump 'N Munch Too convenience store in Council Bluffs, Iowa, near the Nebraska line, said motorists had been pulling off Interstate 80 and using her phone to call their bosses and say they wouldn't be coming in.
With up to 18 inches of snow expected in parts of Iowa, Gov. Chet Culver issued a disaster declaration, clearing the way for state aid, and authorities warned people to stay off the roads.
``There's a real chance for people to get themselves stranded in some real treacherous conditions,'' said Jim Saunders, a spokesman for the Iowa Department of Public Safety.
Lt. Col. Greg Hapgood, spokesman for the Iowa National Guard, said 80 stranded motorists were pulled from Interstate 80. He said he did not know how many more people might be stuck.
``It's hard to see the cars until you come right up on them,'' he said.
Snowplows had been pulled off the roads in western Iowa because of deteriorating conditions, said Dena Gray-Fisher, Department of Transportation spokeswoman.
``There are so many cars in the road and semis jackknifed and whiteout conditions that it's just not safe, and they are unable to make any progress,'' she said.
Minnesota plows were also pulled off roads in the western part of the state.
In North Dakota, a vehicle went out of control on the slick roads Wednesday, hit a ditch and rolled over, killing a couple on their way home from Texas.
The storm blew into Wisconsin later in the day, dumping several inches in spots.
In suburban Milwaukee, part of a supermarket roof collapsed after a morning snowfall. Joe Foltz, who works at the Pick n' Save supermarket, said he heard a crackling shortly before the collapse.
``We thought maybe milk crates crashed on the floor,'' Foltz said. ``About 10 minutes later, it started going down. ... So I rushed everybody out of the emergency exit door and, thank God, we got everybody out.''
In Superior, Wis., Angela Jones decided to stay home with her two children after their day care center closed and a blizzard warning was posted.
``It is snowing and blowing. The wind is blowing really hard,'' said Jones, 31. ``The flag out there is whipping around. I am glad I didn't have to go out in this.''
As much as 22 inches of snow could fall in her area of northwestern Wisconsin through Friday morning, while 6 to 12 inches was expected in some central areas, the National Weather Service said.
The storm was part of a larger line of thunderstorms and snowstorms that stretched from Minnesota to the Gulf Coast. Tornadoes killed several people in Missouri and Alabama, including many at a high school, authorities said.
More than 140 school districts canceled classes Thursday in Minnesota even before the heavy snow arrived.
By Friday, snowfall totals were expected to be a foot or more in southern and central Minnesota, where up to 2 feet fell last week. In northeastern Minnesota, the totals could hit 2 feet. The weather service warned of blowing snow and possible blizzard conditions in the countryside.
``We're going to get pummeled,'' National Weather Service meteorologist Byron Paulson said.
Flights were canceled around the region. At the Minneapolis-St. Paul International Airport, airport officials were preparing for serious disruptions after airlines nixed about 400 flights, a number that was expected to grow.