At 9:32 a.m. on Saturday, January 10, a natural gas explosion killed 20 people in Fremont, Nebraska, and destroyed the Pathfinder Hotel and six adjacent buildings. The exact cause of the explosion is unknown, but the natural gas leak that preceded the explosion was caused by an underground pipe separation. The odor of the natural gas was first detected about four hours before the explosion. However, hotel employees were unable to reach gas company personnel to request assistance for nearly two hours, even though they used emergency telephone numbers.
The fire that resulted from the explosion spread vertically through inadequately protected elevator shafts, stairways, and pipe chases. The incident was remarkably similar to the Paramount Hotel disaster that occurred in Boston on January 18, 1966. During that explosion, the Paramount Hotel was severely damage when flame from the subsequent fire traveled through non-fire stopped pipe shafts and inadequately protected elevator shafts.
NFPA members Download this July 1976 Fire Journal article For NFPA statistical data Fires Starting with Flammable Gas or Flammable or Combustible Liquid