Fire began aboard the S.S. Grandcamp, a bulk freighter which had been loaded with ammonium nitrate fertilizer bound for Europe as part of the Marshall Plan. The Texas City FD responded and attempted to extinguish the fire, and when that didn't work they sealed the hatches and pumped in steal to displace the oxygen in the holds.
Two days later the ship exploded and destroyed most of the Texas City waterfront, killed the entire fire department, and set another ship loaded with Ammonium Nitrate on fire, which also later exploded.
Historical 
Two days later the ship exploded and destroyed most of the Texas City waterfront, killed the entire fire department, and set another ship loaded with Ammonium Nitrate on fire, which also later exploded.
http://en.wikipedia.org/wiki/Texas_City_Disaster