Traffic backed up for about 8 miles in the southbound lanes of I-77 in southwest Virginia. Authorities closed the northbound lanes so fire trucks, ambulances and police could get to the wreck.
A series of crashes began around 1:15 p.m. Sunday in the area of Fancy Gap Mountain. There was heavy fog at the time and photos of the scene after the accident showed poor visibility.
"This mountain is notorious for fog banks. They have advance signs warning people. But the problem is, people are seeing well and suddenly they're in a fog bank," said Glen Sage of the American Red Cross office in Galax.
The Red Cross was setting up a shelter at a Veterans of Foreign Wars post for people stranded by the pileup.
Several vehicles caught fire in the wreck, but the blaze was put out, Virginia State Police spokeswoman Corinne Geller said.
About 10 people were taken to Northern Hospital of Surry County in Mount Airy, N.C., for mostly minor injuries, said Carol Porey, a supervisor there. The extent of the other injuries wasn't immediately clear.
Authorities did not know how long the interstate would be closed. Tow trucks worked to clear some of the wrecked cars and trucks.
Sage said school buses took about two dozen people to the shelter and more were expected. The site was set up to accommodate 100 people.
Relatives likely would pick up local residents brought to the shelter. People passing through might need to stay overnight, he said.
Motorists were advised to seek alternate routes.