DENVER — A major snowstorm blew across Colorado toward the Plains yesterday, dumping more than a foot of snow in some places and grounding hundreds of flights full of holiday travellers. Authorities shut down major highways in parts of four states.The National Weather Service posted blizzard warnings for most of eastern Colorado and adjoining sections of Nebraska and Kansas. A day earlier, the storm had pummelled New Mexico with up to a foot of snow.

Two feet of snow was possible in the foothills just west of Denver, with two to three feet a possibility farther north. Up to 20 inches could accumulate on the Plains of eastern Colorado and wind up to 30 mph could pile the snow into high drifts, the National Weather Service said.

The storm struck Denver with more than six inches of snow just as the morning commute was starting.

“I’m going to grab my computer, talk to my boss and go back home,” Jennifer Robinson said after driving about 20 miles from her home in Boulder to her sales job in downtown Denver. “I’m not going to take a risk and get stuck in Denver.”

Runways at Denver International Airport were shut down late yesterday. Before that, more than 800 flights had been cancelled.

Stranded travellers sprawled on benches and floors at the Denver airport, or stood in long lines at ticket counters trying to make new reservations.

“I’m trying to book another flight, but I’ll probably be spending the night at the airport,” said Michael Heitc, 54, of Denver, who was trying to get to Oregon to visit relatives for the holidays.

In Colorado, Gov. Bill Owens declared a state of emergency and activated the National Guard in case stranded motorists needed to be rescued.

Police closed Interstate 70 for more than 250 miles from just east of Denver to Colby, Kansas and sections of I-80 along a 140-mile stretch from Cheyenne, Wyoming, to Big Springs, Nebraska, because of visibility near zero and slippery pavement.

I-25, Colorado’s busiest north-south route, was closed for about 190 miles from south of Denver to the New Mexico border.

“They pulled everyone off the highway,” said Leon Medina, manager of a truck stop on Interstate 25 in Walsenburg, about 130 miles south of Denver. “Cars are all around the building. Trucks are all over, trucks and cars pulled into ditches.”

Travellers stalled by the closures had already started filling Kansas motels during the morning, said Stan Whitley, a spokesman for the state Department of Transportation.

Scores of schools were closed, along with many courthouses in eastern Colorado.

The lumbering storm dropped more than a foot of snow in Colorado’s southwestern mountains Tuesday, with 19 inches at the Wolf Creek ski area and 17 at Durango Mountain Resort.

“We’ve been waiting for a big storm to hit so this was the best early Christmas present,” Durango Mountain Resort spokeswoman Loryn Kasten said.

Rain spread across much of the rest of the Plains.

Roads around New Mexico were still snowpacked and icy yesterday. Numerous schools opened late or remained closed.