On July 13, 1973, in Potchefstroom, South Africa there was an anhydrous ammonia accident involving a catastrophic failure of a pressurized ammonia storage tank that instantaneously released 38 tons of anhydrous ammonia into the atmosphere. Eighteen people died and an unknown number were injured. A visible cloud extended about 1,000 feet wide and about 1,400 feet downwind; all deaths occurred within 600 feet of the release point.