Nearly 100 vehicles crashed Sunday along a mountainous, foggy stretch of interstate near the Virginia-North Carolina border, killing three people and injuring 25 others.

Police said traffic along Interstate 77 in southwest Virginia backed up for about 8 miles in the southbound lanes after the accidents. Authorities closed the northbound lanes so that fire trucks, ambulances and police could get to the series of chain-reaction wrecks.

Virginia State Police determined there were 17 separate crashes involving 95 vehicles within a mile span near the base of Fancy Gap Mountain, spokeswoman Corinne Geller said. The crashes began about 1:15 p.m. Sunday when there was heavy fog in the area.

“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 the town of Galax.

Overhead message boards warned drivers since about 6 a.m. Sunday to slow down because of the severe fog, Geller said. The crashes were mostly caused by drivers going too fast for conditions.

At the “epicenter” was a wreck involving up to eight vehicles, some of which caught fire, Geller said. Photos from the accident scene showed a burned out tractor-trailer and several crumpled vehicles badly charred. Those taken to hospitals had injuries ranging from serious to minor.

School buses took stranded people to shelters and hotels.

Authorities reopened the northbound lanes Sunday night and hoped to have the other side cleared later in the evening.

Police have not released the names of those killed.