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During the early morning of March 25, 1970 propellants crew began the chill-down of the liquid Oxygen (LOX) pumping system at Launch Complex 39A to begin loading LOX in Apollo 13’s Saturn V first stage for the final ‘wet’ portion of the Countdown Demonstration Test. During the 40-minute precooling process, over 10,000 gallons of LOX were emptied into the dump reservoir. Ocean breezes would normally dissipate the Oxygen fog, but on the morning of the 25th, there was no breeze and there was a temperature inversion. The Oxygen fog built up in the drainage ditch and Oxygen began overflowing onto the banks of an adjacent road. By 6:00 AM close-out crews and safety personnel were clear of the LOX storage area and security officers were ensuring personnel were clear of the area for the hazardous propellant loading process. As the patrolmen had stopped at a perimeter fence, two of the patrol cars spontaneously combusted and the third ignited when the car was started. The patrolmen quickly abandoned their cars and took cover. The fire department arrived within five minutes, but took no action until the Oxygen fog dissipated and the fire was under control by 7:00 AM. Of the investigation that followed, the practice of dumping large quantities of propellant was criticized, entry/exit of the launch complex were studied and KSC safety training was modified. The LOX drainage lines were further extended away from the pad to a marshy area. Engine heat and grease/oil combustibles mixed with Oxygen vapors contributed to two patrol cars spontaneously combusting and the third patrol car was destroyed when the driver turned the ignition.