Six people were taken to hospitals with minor injuries and the northbound lanes were closed after the crash occurred on the major north-south corridor shortly before 9 a.m. in McMinn County. The highway reopened at 1:30 p.m.
''Some witnesses said the snow was coming down so hard they could barely see the front of their hoods,'' Department of Safety spokeswoman Melissa McDonald said.
Traffic had slowed for the snow storm but apparently couldn't stop when the initial wreck occurred at mile marker 59, about 45 miles south of Knoxville.
''The road was completely iced over,'' Union Grove Fire Chief Alvin Shoemaker said.
Tennessee Highway Patrol trooper John Rogers said a car apparently began sliding sideways and was hit by a truck. Other vehicles started sliding too, and the chain reaction began.
Five tractor-trailers and a dump truck were among the 20 vehicles that crashed into one another. A dozen other cars went off the road but were not damaged, troopers said.
Ohio driver Cheryl Conkle's pickup truck was hit by another truck, and she saw a tractor-trailer overturn and slide down the highway.
''It turned over like it was in slow motion,'' she said.
Diesel fuel spilled and car and truck parts littered the highway and median, but none of the trucks lost their loads. The leaked fuel posed no threat to the environment, said Bob Van Horn, incident supervisor with the Tennessee Department of Transportation.
National Weather Service meteorologist David Hotz said intense snow showers occurred all over East Tennessee on Tuesday.
''When you get a scattered, intense snow shower, it is almost like a summertime shower'' that dumps rain on one area and not on another, he said.
