On April 16, 1947, the French-flagged vessel SS Grandcamp was docked at Texas City, Texas, carrying approximately 2,300 tons of ammonium nitrate fertilizer. A fire broke out in the ship's hold, prompting the crew to inject steam into the cargo areas to extinguish the flames without damaging the dry goods. This strategy proved disastrous: the trapped heat and moisture accelerated the thermal decomposition of the ammonium nitrate, which was coated with paraffin wax to reduce caking.
The wax acted as a carbonaceous fuel source, while the ammonium nitrate provided an abundant oxidizer. As temperatures surpassed critical thresholds under sealed conditions, deflagration rapidly transitioned to a full-scale high-explosive detonation. The reaction generated a supersonic shockwave traveling outwards at over 4,000 meters per second.
The sudden release of compressed gas shattered the ship's hull, sending thousands of tons of metal shrapnel into nearby oil storage tanks and chemical plants. The kinetic energy generated a 15-foot displacement wave in the harbor that inundated the docklands. The shockwave knocked two light aircraft out of the sky, shattered windows 40 miles away in Houston, and registered as an seismic event in Colorado.