A 58-year-old Knoxville man has died from a cardiac event while hiking in the Great Smoky Mountains National Park. Rangers say that Harold Thompson was on the Injun Creek Manway leading to the Grapeyard Ridge Trail Friday when he experienced the attack while not far from the Greenbriar Ranger Station. CPR and an automated external defibrillator (AED) were utilized on Thompson, who had been hiking with his brother. He was pronounced dead at 3 PM.