DES MOINES — A thick glaze of ice brought down power lines and cut electricity to hundreds of thousands of people, closed schools, and canceled flights today as a major ice storm coated the nation’s midsection.

At least 22 deaths had been blamed on the storm system since the waves of sleet and freezing rain started during the weekend.

Officials in Missouri, Kansas, and Oklahoma had declared states of emergency. President Bush declared an emergency in Oklahoma today, ordering federal aid to supplement state and local response efforts.

Ice as much as an inch thick had accumulated on trees, power lines, streets, and car windshields yesterday in parts of Oklahoma and Missouri, with thinner layers elsewhere. About an inch of ice was expected today over parts of Iowa, followed by up to 5 inches of sleet and snow.

“This is a big one. We’ve got a massive situation here and it’s probably going to be a week to 10 days before we get power on to everybody,” a spokesman for Public Service Company of Oklahoma, Ed Bettinger, said. “It looks like a war zone.”

Iowa’s largest school district closed for the day in Des Moines, telling its nearly 31,000 students to stay home, and kids across most of Oklahoma and in the Kansas City, Mo., area stayed home for a second day.

Schools also were closed in parts of Wisconsin, including Milwaukee Public Schools with 85,000 students. “We thought about our kids on foot,” a Milwaukee schools spokeswoman, Roseann St. Aubin, said. Some drivers couldn’t even get to their buses, she said.

Nearly 600,000 Oklahoma homes and businesses still had no electricity today, most of them since yesterday when power lines began snapping under the weight of ice and falling branches — the biggest power outage in state history. Utilities in Missouri reported more than 100,000 homes and business without power and Kansas utilities said more than 100,000 were blacked out today, with some in the dark since Sunday.

Iowa’s two major utilities reported over 17,000 customers without power today.

The Kansas National Guard was asked to supply generators to several locations, including sewer treatment systems, and two nursing homes, a Kansas Emergency Management spokeswoman, Sharon Watson, said.

A backup generator enabled a Home Depot store to open in Oklahoma City, but a sign warned customers of shortages: “No Generators, Ice Melt, Scrapers, Lamp Oil, Firewood, Kerosene Heaters, Chainsaws.”

“Everybody is being patient and understanding,” a store manager, Mike Meador, said. “People are in need, and we need to be here for them.”

Des Moines International Airport closed because of ice late yesterday and could be closed most of today, a spokesman, Roy Criss, said. The airport, which also was shut down by winter weather two weeks ago, has 138 arrivals and departures a day, he said.

“This rain keeps refreezing. We put chemicals down, it melts and the freezes again. We can’t stay ahead of it,” Mr. Criss said. “This is not fun.”

Many travelers were grounded at Chicago, where about 250 flights were canceled this morning at O’Hare International Airport and departure delays averaging 15 to 30 minutes, a spokeswoman for the city’s Department of Aviation, Karen Pride, said.

Kansas City International Airport in Missouri canceled more than 90 flights this morning, but a spokesman, Joe McBride, said that was probably due to problems at other airports.

Southeastern Nebraska also had power outages today and some flights in and out of Omaha’s Eppley Airfield were canceled.

The Federal Emergency Management Agency and the Army Corps of Engineers sent 50 generators and three truckloads of bottled water from Texas to distribute to blacked-out areas of Oklahoma.

At least 22 deaths — most of them in traffic accidents — had been blamed on the ice and cold since the weekend, including 15 in Oklahoma, four in Kansas, and three in Missouri.