A cargo ship explodes at dockside in Texas City, Texas. The blast and the fires that follow kill about 600 people and injure 3,500 more. Six decades later, it remains the deadliest explosion and worst industrial disaster in U.S. history.

The Grandcamp, a World War II Liberty ship that had been converted to a French merchant vessel, was taking on a load of ammonium nitrate fertilizer at a quay next to a complex of Monsanto chemical factories, offices and labs. The ship’s carpenter smelled smoke in the No. 4 hold around 8 a.m. on April 16 and found that a few bags of fertilizer were on fire. He tried dousing it with a few buckets of water, then a fire extinguisher.

When he called for a hose, the ship’s captain forbade it, fearful that water would destroy the $500 worth of cargo that was on fire. The skipper ordered the hold closed and its fire-suppression valves opened to release steam. Ordinarily a good idea, but not in this case.

Ammonium nitrate decomposes at around 350 degrees Fahrenheit. The fire grew. The captain ordered his crew to abandon ship.

Texas City had a small fire department. Just 36 hours before the fire, National Maritime Union co-founder James Gavin had told union members in New York that Texas City was unsafe and a “natural” for a catastrophic explosion.

Firefighters tried spraying the burning ship from the dock. Spectators, including schoolchildren crowded the quayside to watch the action. Bad idea.

The Grandcamp exploded at 9:12 a.m. Exploded is probably too mild a word. The captain and 32 of the Grandcamp‘s crew died; 10 somehow survived. More than 200 people were killed on the quay. The blast was heard 160 miles away. It shattered all the windows in Texas City and half of those in Galveston, 10 miles away.

Some debris reached an altitude of nearly 3 miles before falling back to earth. Two airplanes circling overhead were blown apart by the heavy shrapnel. A one-ton piece of the ship’s propeller shaft landed 2½ miles away. Other pieces sailed 5 miles.

The blast flattened 20 waterfront blocks and 12 blocks inland. Flaming debris ignited oil, gas and chemical tanks at the sprawling Monsanto complex and three nearby oil companies. People died everywhere, blown up by the blast, decapitated by flying metal, sliced by falling glass, burned by flaming metal and chemicals, crushed by falling buildings. The litany of death was long and varied. Thousands more suffered injuries.

Fire and rescue workers rushed in from nearby cities, and the Red Cross mobilized a massive national response, but these were the days before jet passenger and cargo planes. Local authorities set up temporary morgues and pressed medical students into duty in overwhelmed emergency rooms. The fires kept burning, at the docks, the tanks and all over town. But the horror had not yet ended.

The cargo ship Highflyer, which had been moored near the Grandcamp, caught fire the morning after the explosion. When the fire seemed to be getting out of control, tugs were called to tow the ship out of the port, lest its own cargo of fertilizer explode, too.

Unfortunately, the force of the Grandcamp explosion had locked the Highflyer into a deadly embrace with another ship, the Wilson B. Keene, and the Highflyer wouldn’t budge. The tugs gave up. The Highflyer blew up, also demolishing the Keene, and raining death and fire anew on Texas City. The shockwave and new fires killed hundreds more.

The fires were not put out until April 18. Bodies and parts of bodies were strewn all over town. “Blood and guts” was not just a phrase. At least one survivor reported getting stuck in a slippery tangle and looking down to see that it was human intestines.

The state government ultimately listed 405 identified and 63 unidentified dead. Another 100 or perhaps 200 were counted as missing. Injuries may have reached 3,500. That’s 4,000 casualties in a town of 16,000.

More than 1,500 houses — a third of the town’s housing — were destroyed. Two thousand of the survivors were rendered homeless. Property damage reached at least $600 million (almost $6 billion in today’s money).

An official report on the disaster recommended improved containers, labeling and special handling of ammonium nitrate fertilizer; prohibiting smoking in all piers and docks at all times; and worst-case-scenario community disaster plans to coordinate relief agencies, police and fire departments, hospitals, doctors and nurses, civil officials and military authorities.

Today, the unknown dead rest in a special cemetery. Monuments in Texas City include the propeller of the Highflyer and an anchor from the Grandcamp.

Source: Darkest Hours, by Jay Robert Nash (1976)