A tour bus carrying JOSH TURNER's road crew crashed on Wednesday after the show in Paso Robles, California.  Seven people were injured, and Josh's longtime sound man David Turner was killed.  He was 64.  They're not related.

Josh and his band were in a separate bus and weren't injured.  The investigation is still ongoing, but here's what we know.  For some reason, the bus left the road at around 11:30 P.M. and drove 20 yards before falling off a cliff.

The California Highway Patrol has ruled out drugs or alcohol, and the bus is being checked out to see if there were any mechanical issues.  They're also looking into whether the driver may have suffered a medical problem that could have caused it.

All of Josh's September shows have been canceled and will be rescheduled.  A rep issued a statement saying, "Josh Turner and his road family have suffered a devastating loss.  Please keep the crew, band, and Josh in your thoughts and prayers."