The huge explosion that leveled a fertilizer plant in West, Texas, Wednesday night and may have killed up to 15 people occurred almost exactly 66 years after a far worse industrial tragedy in the same state.

About 240 miles southwest of the fertilizer factory, in the coastal town of Texas City, an explosion killed more than 500 people – and perhaps up to 600 -- on the morning of April 16, 1947.

As port workers prepared to load a cargo ship, the SS Grandcamp, with explosives-grade ammonium nitrate fertilizer, they realized a fire was raging in the vessel’s engine room.  The flames spread and ignited a massive explosion -- when the first inferno erupted, about 2,300 tons of ammonium nitrate were already on the ship.

The explosion flattened the town of Texas City and the shock was felt as far as 250 miles away.

A second explosion occurred on the following day, resulting in additional damage.

The Texas City incident remains the deadliest industrial accident in American history.

The Fire Prevention and Engineering Bureau of Texas’s official report on the accident at the stated: "The loss of life was high. All firemen and practically all spectators on their pier were killed as were many employees in the Monsanto Chemical Company and throughout the dock area. At this date, April 29, 1947, 433 bodies have been recovered and approximately 135 (many of whom were on the dock) are missing. Over 2,000 suffered injuries in varying degrees, among whom were many schoolchildren injured by flying glass fragments and debris in school buildings located about 6,000 feet distant." All but one member of the Texas City fire department died battling the monstrous blaze.

According to a document by the Texas City Firefighters, the initial explosion created  a towering cloud of black smoke billowing into the sky, while people on the street in nearby Galveston were thrown to the pavement, and glass store fronts shattered.

“Buildings swayed in Baytown, 15 miles to the north,” TCF said.

“In Texas City itself, stunned townspeople who started toward the docks soon encountered wounded persons staggering out of the swirling vortex of smoke and flame, most covered with a thick coat of black, oily water. Many agonizing hours were to pass before a semblance of order began to replace the shock and confusion caused by this totally unexpected and devastating event.”

The disaster was so overwhelming that the exact number of casualties has never been determined.

The Red Cross and the Texas Department of Public Safety at the time counted 405 identified and 63 unidentified dead. However, another 100 people were as characterized as "believed missing" because no trace of their bodies was ever found.

An estimated 3,500 people were believed injured by the blasts.

The catastrophe led to a wave of lawsuits against the U.S. government for negligence in connection with the improper storage of ammonium nitrate and other malfeasances. By 1957, when the final claims were filed, the government paid out about $17 million in damages.