The white bus was heading east on the highway when it crossed into the westbound lanes striking a tractor-trailer truck and a Chevrolet Tahoe sport utility vehicle between mile markers 422 and 424, authorities said.
Twelve people injured in the accident were transported to the University of Tennessee Medical Center, WATE-TV, Knoxville, reported.
"We were able to get in and out to everybody," J. Ray Walker of the Jefferson County Volunteer Rescue Squad told the television station.
Officials said there were eight dead -- six on the bus, the truck driver and one person in the SUV -- but the conditions of the injured were not reported.
The bus was on its side but did not catch fire while the semi truck went up in flames. The Tennessee Highway Patrol closed all lanes of Interstate 40.