An Oklahoma man was killed in a one vehicle accident Thursday morning on Interstate 70, at the Vandalia exit. Illinois State Police reports say their preliminary investigative details indicate that 66 year old Stanley Hamilton of Antlers, Oklahoma was exiting Interstate 70 in his 2003 Freightliner truck tractor with trailer at milepost 63 into the City of Vandalia. State Police Reports say Hamilton’s vehicle crossed the yellow fog line and entered the left ditch. State Police say the vehicle load jack-knifed and broke loose from the cab. The vehicle then skidded out of control and overturned. Fayette County Coroner Bruce Bowen says that Hamilton was pronounced dead at the scene. Bowen adds an autopsy will be conducted Friday at St. Anthony Hospital in Effingham to determine whether a medical condition caused the crash or driver error.