National Guard troops in tracked vehicles crawled through 10-foot snowdrifts and whiteout conditions Saturday in eastern Colorado, rescuing motorists trapped by the region's second holiday season blizzard.

The storm, which brought Denver to a standstill and hampered holiday air travel Thursday and Friday, was slowly moving east, spreading snow from New Mexico to the Dakotas and generating strong thunderstorms in the lower Mississippi Valley. Blizzard warnings were posted for eastern Colorado and western Kansas and into parts of New Mexico, Oklahoma and the Texas Panhandle.

The Guard pulled about 20 people out of cars stranded on rural highways from Friday night into Saturday and took them to emergency shelters, said Maj. Gen. Mason Whitney, the state adjutant general.

"They're telling me it's zero visibility," Whitney said. "They'll kind of bump into something and it'll turn out to be a car with people in it."

No injuries were reported.

Interstate 70 and several other major east-west highways were closed Saturday from the Rockies east across Colorado into western Kansas. Interstate 25 heading south into New Mexico was closed near the state line.

All major roads from Kansas into Colorado were closed Saturday, including Interstate 70. A Kansas Highway Patrol dispatcher said the roads would remain closed until Colorado officials decide to reopen their routes.

One traffic death was blamed on the storm in Colorado and a tornado killed one person in Texas on Friday.

About 500 travelers spent the night at Denver International Airport, not stranded but hoping to get an early start on ticket lines, said airport spokesman Chuck Cannon.

The nation's fifth-busiest airport was closed for two days by the storm that struck just before Christmas, but it was only slowed by the latest storm, with the major carriers canceling about 20 percent of their scheduled flights.

Airlines planned to fly full or nearly full schedules Saturday, Cannon said.

In southeastern Colorado, about 50 Guard troops operated four SUSVs, or "snow utility sustainment vehicles" — a military version of the sno-cat. The vehicles travel on tracks and can carry 12 people or supplies, Whitney said.

The troops were working around the clock through snowdrifts standing 7 to 10 feet deep, Whitney said.

Nearly two feet of snow fell in the foothills west of Denver, where many streets were still packed with ice from last week's blizzard.

Up to 18 inches of snow had fallen by Saturday in western Kansas, but the snow had started turning to rain in many areas Saturday. Up to a foot fell in southwestern and central Nebraska.

Colorado Gov. Bill Owens had declared a statewide disaster emergency. Many government agencies and businesses were closed Friday. Denver Mayor John Hickenlooper said the economic impact on the city could easily total several million dollars.

Compared to last week's blizzard, this storm produced its snow over a longer period, making it easier for armies of snowplows at the Denver airport and in most major cities across the state to keep up.

The tornadoes generated by the storm system in Texas on Friday destroyed as many as 50 homes, sent at least a dozen people to hospitals and forced President Bush and his wife into an armored vehicle on his Crawford ranch. The Bushes, and their two Scottish terriers, were driven to a tornado shelter on the ranch. They sat inside the armored vehicle until the weather cleared, deputy White House press secretary Scott Stanzel said.

Residents of an assisted living center for military veterans in Texas had little time to react Friday before a tornado struck.

"That convalescence center received word, from our understanding, about 30 seconds before the tornado hit them," said Matt Groveton, the emergency management coordinator for Limestone County, about 60 miles east of Crawford near Waco. "Everybody dove to the ground."