Tens of thousands of people in rural areas remained stranded in their homes today, their food supplies dwindling, after the state's worst snowstorm in 90 years.

Students using the Ritchie Center sports complex at the University of Denver were evacuated this morning because a wall was threatened by heavy snow tumbling off a roof. A women's gymnastics meet scheduled for the evening was postponed.

A suburban Office Depot also was evacuated because of fears the roof would collapse.

The roofs on hundreds of homes and businesses have collapsed since the storm, but none has caused serious injuries.

In Jefferson County, where 50,000 to 75,000 people were snowed in, officials declared a state of emergency. They asked the state for crews, plows and snowmobiles to help clear the roads west of Denver, where as much as 11 feet of snow had fallen.

Jefferson County Administrator Patrick Thompson said some residents had managed to get out. "Hopefully, in the next eight to 12 hours, we'll have holes punched through so other people can get out," he said.

The U.S. Postal Service hoped to reach 80 percent to 90 percent of metropolitan area residents today. About 75 percent of the area's homes and businesses received mail on Friday.

Officials also asked for helicopters to reach people in emergencies. Two houses were lost to fires because firefighters couldn't reach them.

"We've been holding out on using the snowmobiles for anything other than medical emergencies," county spokesman John Masson said Friday. "But we're using every last bit of our equipment, and crews are working to clear the gravel roads so these people can get out."

A spokesman for Gov. Bill Owens (R), Dan Hopkins, said officials in Clear Creek, Weld, Custer and Larimer counties had declared emergencies. The cities of Fort Collins and Loveland also requested help.

The storm, which began Tuesday, dropped snow over nearly 500 miles in Colorado and southern Wyoming, affecting more than 3.5 million people. At least six people died in both states.

The National Weather Service said 31.8 inches of snow accumulated in Denver, the heaviest snowfall since a December 1913 storm that dumped 471/2 inches of snow on the city over five days.