An ice storm slickened roads and sidewalks, grounded flights, and cut power to tens of thousands Sunday in a swath from the Southern Plains to the Great Lakes as even colder weather threatened.

The wintry weather was expected to continue through midweek, and ice storm warnings stretched from Texas to Pennsylvania.

"Tomorrow may be even more of a dilemma than today because we're going to get even a little bit more colder," said John Pike, a meteorologist in the Weather Service's office in Norman, Okla.

Five traffic deaths were blamed on icy roads in Oklahoma. More than 130,000 customers lost power in Missouri, Oklahoma, Illinois and Kansas, utilities reported.

Some communities in Missouri reported ice as thick as three-quarters of an inch, the National Weather Service said.

"The rural roads are pretty rough, the main highways are pretty clear, and the overpasses are slick," said John Christiansen, emergency management director in Missouri's St. Clair County.

Missouri Gov. Matt Blunt declared a state of emergency and activated the National Guard.

At Kansas City International Airport, about two dozen flights were canceled by midafternoon Sunday, and more than a dozen flights were called off at St. Louis Lambert International Airport.

Places of worship across the region called off services because of the slippery roads. Roads in all but the southeastern corner of Oklahoma were considered slick and hazardous, the state Department of Transportation said.

Chicago officials used the city's emergency phone system to deliver recorded warnings to about 2,700 elderly residents that sidewalks were icy and slippery.