A medical emergency is thought to be the cause of a school bus crash in Miller County that left students on board unhurt but took the life of the driver. The Missouri Highway Patrol says on Tuesday afternoon, a bus driven by 65-year old Phyllis Rush of Eugene was on Opal Road just east of Ulman Ridge Road. She suffered the medical emergency which caused her to lose control of the bus which went off the road and hit a tree. Rush was pronounced dead at the scene. Six juvenile students on the bus were not hurt.