National Guard crews delivered food and other supplies Saturday to hundreds of travelers and residents stranded after a spring storm covered the Denver area with more than 3 feet of snow.

Two truckloads of cots, blankets and meals arrived in Denver with the troops on Saturday morning.

More than 500 people spent the night at three shelters after the closure of an 80-mile stretch of I-70 in the mountains, said Jim Rettew, an American Red Cross spokesman.

"It's very, very hard to speculate as to when traffic is going to be allowed back on the road," Colorado Department of Transportation spokesman Fritz Homann said early Saturday. "There seems to be a lull in the storm, but whether the second wave comes in as advertised will be anybody's guess."

A mixture of rain and snow continued falling across the state Saturday morning, and Entrekin said the southern Denver metro area could see 2 to 5 more inches before the storm tapers off Saturday evening.

Denver International Airport was open and no flight cancelations were reported. On Friday, United Airlines, the airport's dominant carrier, canceled 76 flights.

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Though the weather system was weakening Saturday, the cleanup was only just beginning.

Homann said some motorists were still stuck on Interstate 70 at Hidden Valley early Saturday, but crews were working hard to get them out.

"This is a big storm, but it is a spring storm in the Colorado Rockies, and that is something that CDOT has dealt with before," he said. "We have all our resources poised and ready to go."

The heaviest snowfall was in the foothills west of Denver, with 43 inches at Pinecliffe and 36 at Black Hawk, said weather service meteorologist Scott Entrekin. He said April could sometimes be one of the state's snowiest months.

Transportation officials shut down an 80-mile stretch of I-70 between Vail and Golden late Friday afternoon because of wet, heavy snow and multiple accidents.

The American Red Cross opened a second shelter in Idaho Springs late Friday after its first shelter there filled to capacity with more than 300 people, said Jim Rettew, a spokesman for the organization's Mile High Chapter.

The stranded travelers didn't all get cots, but many got snacks, and most were in good spirits, he said.

"Some are trying to sleep, some are talking, some are eating, some are on the phone," Rettew said. "When this kind of thing happens, everyone just makes the best in trying circumstances."

The Colorado National Guard escorted a caravan of volunteers and supplies to the shelters after Clear Creek County declared an emergency and asked for state assistance. County officials were working to set up one or two more shelters in Georgetown.

It was unclear when the interstate would reopen. The spring storm had dumped up to 3 feet of snow on the foothills by Friday night but was starting to weaken, forecasters said.

On Friday, heavy, wet snow closed highways, canceled flights, caused power outages and forced school closures in parts of Colorado and Wyoming. Snow accumulations of 3 to 4 feet were recorded in the mountains, with 4 to 6 inches measured in Denver.

United Airlines, the dominant carrier at Denver International Airport, canceled 76 flights. The airport urged travelers to check with their airlines before leaving home.

Numerous traffic accidents were reported across Colorado, and Trooper Gilbert Mares of the State Patrol said he knew of one fatality. He said a person was killed late Friday afternoon in a two-vehicle crash on Colorado 52 in Weld County, near Fort Lupton. Details on the victim were not immediately available.

U.S. 40 over Berthoud Pass, the main road to the Winter Park ski resort, was shut down Friday evening because of a pair of avalanches. A spokeswoman for the Colorado Department of Transportation said no injuries were reported in those incidents. The agency said Berthoud Pass and Vail Pass would remain closed overnight.

Power lines weighed down by snow tripped system circuit breakers and knocked out electricity to 9,600 Xcel Energy customers in Evergreen and 4,600 people in Nederland, 25 miles west and 35 miles northwest of Denver, respectively, said Joe Fuentes, a spokesman for the utility. Some of those customers were expected to be without power overnight, but crews were working around the clock, he said.

About 2,600 customers also lost power in Denver.

Nearly 3 feet of snow had fallen by Friday afternoon in Rocky Mountain National Park about 60 miles northwest of Denver, forcing officials to close its Beaver Meadows and Fall River entrances because snowplows couldn't keep up.

Many suburban Denver schools sent students home early Friday, and at least three Colorado Springs-area high schools delayed weekend proms because of the storm.

The University of Northern Colorado in Greeley moved its football scrimmage to Tuesday because of snow, while Colorado State University canceled its Saturday spring game.

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The Associated Press contributed to this report.