Philadephia - A destructive winter storm that has left more than 900,000 customers in the dark barreled into the Northeast on Wednesday, delaying flights and turning the morning rush into the morning slush as communities braced for the worst.

The storm has been blamed for at least 21 deaths and a glaze of ice and snow that caused widespread power failures from the Southern Plains to the East Coast. Authorities said it could be a week before some communities have electricity again.

Tree limbs encased in ice tumbled onto roads and crashed onto power lines in hard-hit Arkansas, Kentucky and Oklahoma on Tuesday and overnight. In Arkansas - where ice was 3 inches thick in some places - people huddled next to portable heaters and wood-burning fires as utilities warned electricity may be out for a week or more.

David Stark had an adventurous trip on Interstate 71 to get to work in La Grange, in northern Kentucky.

"The roads look clear but you can't do over 40 mph," he said during a stop at a convenience store for gas and food. "There's a lot of black ice. I slipped and slid everywhere."

Since the storm began building on Monday, the weather had been blamed for at least six deaths in Texas, four in Arkansas, three in Virginia, five in Missouri, two in Oklahoma and one in Indiana. Winter storm warnings were in effect from Texas to New England on Wednesday.

Power failures continued in eastern Oklahoma and western Arkansas, where travel remained hazardous, officials said. Ice storms overnight in West Virginia knocked out power more than 55,000 customers.

More than 300,000 customers in Arkansas lacked power Wednesday morning and more than 400,000 in Kentucky, where Pearl Schmidt's family endured a cold night without power at their Paintsville home.

"We bundled up together on a bed with four blankets. It's freezing," she said.

In Illinois, Indiana and Ohio, more than 180,000 homes and businesses were in the dark as ice and snow coated parts of the states. Ohio's top Republican lawmaker, Senate President Bill Harris, slipped on ice outside a hotel near the Statehouse in Columbus, broke a leg and missed the governor's State of the State address Wednesday.

Tracey Ramey of Waynesville, Ohio, a village about 20 miles southeast of Dayton, said her husband left for his job as a snow-plow operator late Monday with an overnight bag and hasn't been able to return. He did call her Wednesday morning to caution her not to go to her data-entry job.

"He said, 'There's 2 inches of ice on the road and there's no way you're going to make it to work,'" she said.

Air travelers hunkered down at airports throughout the region. Philadelphia International reported scattered cancellations and delays Wednesday morning. Airlines canceled more than a dozen flights each out of Columbus and Cincinnati/Northern Kentucky International Airport.

The snow and sleet turned to rain in southeastern Pennsylvania as temperatures rose above freezing later in the day. But in northern and central Pennsylvania, snow accumulations could reach 4 to 8 inches. Up to 8 inches was expected in parts of western Pennsylvania.

Cynthia Lahiba of Baltimore walked through the ice and snow about six blocks to her downtown office Wednesday.

"My $65 pair of shoes are going to be ruined. It's pretty bad out here," she said.

The storm was already turning to rain in New Jersey by Wednesday morning, creating a soggy commute.

Some parts of Vermont expected 14 inches of snow, and the entire state was under a winter storm warning through early Thursday. Inland areas of Maine expected 2 feet of snow before the storm ends, and snow also fell over New York and Boston, extending commute times.

Forecasters said northwestern Connecticut could get 8 inches of snow, while Hartford and other inland areas could get 6. The National Weather Service expected the snow to turn into rain in the afternoon and evening.

The weather gave President Barack Obama a chance to rib his new hometown on its winter weather wimpiness.

"Can I make a comment that is unrelated to the economy, very quickly?" the new president told reporters at a gathering with business leaders. "And it has to do with Washington. My children's school was canceled today. Because of what? Some ice?"

The president said he wasn't the only incredulous one.

"As my children pointed out, in Chicago, school is never canceled," Obama said to laughter. "In fact, my 7-year-old pointed out that you'd go outside for recess. You wouldn't even stay indoors. So, I don't know. We're going to have to try to apply some flinty Chicago toughness."