A Greyhound bus with 41 passengers flipped over its side on a busy highway, causing minor injuries for six of the approximately 41 passengers, officials said.

None of the injuries appeared to be life-threatening, state police Lt. Larry Keiser said.

The bus was traveling from Chicago to Nashville, Tennessee.

It was not immediately clear what caused the crash. The road was clear and dry at the time. The bus ended up on its passenger side, its wheels against the concrete barriers in the median.