OKARA - Four people were killed and 16 others sustained injuries in a road accident near Shahana bridge at Ravi River here on Tuesday. Police said a bus was on its way to Faisalabad from Sahiwal when it turned turtle due to overspeeding. As a result, four passengers who were yet to be identified, were killed and 16 others received injuries.  Rescue 1122 shifted the injured to Sahiwal teaching hospital.