A blast of snow, freezing rain and plunging temperatures created headaches for travelers Tuesday across the Midwest with canceled flights and cars and tractor-trailer rigs sliding off highways.

A blizzard warning was in effect until midnight for counties north of Indianapolis, and a foot or more of snow was possible across Indiana's midsection and parts of Illinois.

As the storm pushed eastward, the National Weather Service issued winter storm watches and warnings extending from Iowa and Missouri across the Ohio Valley into parts of New England. Snow was already starting to fall in the mid-Atlantic states by midmorning.

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At least four traffic deaths were blamed on the snow and ice — three in Nebraska and one in Missouri — and a tornado killed one person in Louisiana.

More than 10 inches of snow had fallen in north-central Indiana by late morning and wind gusting to 40 mph piled the snow into drifts up to 3 feet high, weather service meteorologist Logan Johnson said in Indianapolis.

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Snow removal service owner Mark Hawk started plowing parking lots and subdivisions at about 4:30 a.m. in Carmel, a northern suburb of Indianapolis.

"I'd get something done, and I'd have to go back over my work because it didn't look like I had done anything" because the snow was falling fast and blowing, Hawk said.

Cold air dragged southward by the weather system dropped the temperature at Grand Forks, N.D., from 11 below zero at midnight to 20 below at midmorning, the weather service said. Temperatures as low as minus 15 were possible in northern Illinois.

Chicago's O'Hare International Airport canceled more than 400 flights Tuesday, city aviation department spokeswoman Wendy Abrams said. Midway Airport canceled about 100 flights. A handful of flights also were canceled at the Indianapolis International Airport, and about 20 percent of the flights out of Cincinnati's main airport were canceled because of poor conditions elsewhere, spokesmen said.

Schools were canceled or delayed in several states.

Officials in west-central Indiana's Fountain County declared a snow emergency and roads were closed except for "extreme emergency traffic."

"People are sliding off everywhere," said Joe Whittaker, the county's emergency management director.

Ohio state officials said roads were wet or snow-covered in every county, and southbound lanes of Interstate 75 were closed in the Dayton area because of jackknifed tractor-trailer rigs.

Along the southern edge of the snow belt, freezing rain coated roads, tree limbs and power lines with as much as a quarter-inch of ice.

About 6,000 Duke Energy customers in Indiana lost power, mostly in the Bloomington area, said spokeswoman Angeline Protogere.

Rain and thunderstorms extended farther south, producing a possible tornado that killed at least one person, injured more than a dozen others and damaged dozens of homes in the New Orleans area.

In New York state, where communities on the eastern end of Lake Ontario have endured a week of lake-effect snow measured in feet instead of inches, forecasters said the storm could produce 8 to 20 inches of snow in some areas.

The upstate New York town of Redfield is the hardest hit. Incomplete records prevent the weather service from calling the 11 feet, 9 inches of snow that fell there over the past 10 days an official record, but it does beat the 10 feet, 7 inches that fell in nearby Montague over seven days ending Jan. 1, 2002.

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