A car spun out of control in heavy snow and fog on Interstate 70 today, causing a chain-reaction crash that involved up to 83 cars and killed two people.

At least 29 people were injured in the collision in the Rocky Mountain foothills west of Denver, but most were likely to be released from hospitals soon.

"The visibility was so bad you couldn't see the person in front of you," said Shannon Rogers, who appeared to have escaped injury.

"We tried to stop and went sliding off the road and we thought that was the worst of it, but then we kept hearing bangs, squeaking tires and people just kept banging into each other. We just kept hearing people screaming and it just never seemed to stop," she said.

The accident, which occurred at about 12:40 p.m. during the area's first major snowstorm of the season, forced the closure of I-70 in both directions. The eastbound lanes were quickly reopened and the westbound lanes reopened at about 5:30 p.m.

The pileup was triggered when a car spun out of control in the westbound lanes and other cars ran into it as the driver tried to turn around to keep heading west, said Colorado State Patrol spokesman Gary Eyer.

Up to 11 inches of snow fell in the foothills, and the Front Range of the Rockies was under a winter storm warning tonight.