Investigators working in the remnants of an exploded Texas fertilizer plant sifted through untold kernels of corn by hand, moved tons of debris and conducted more than 400 interviews. They were searching for the missing piece to solve what many officials compared to an extraordinary puzzle.
One month after a fire triggered a massive blast killing 15 people, officials on Thursday had to declare the cause of the blaze as “undetermined.”
Investigators narrowed the number of possible causes to three: a problem with one of the plant’s electrical systems, a battery-powered golf cart and a criminal act. They ruled out a wide number of others, from a rail car on site loaded with fertilizer to someone smoking.
But they could not say with certainty what caused a fire on April 17 inside the seed and fertilizer building at West Fertilizer Co., in West, a tiny Texas town previously known for its Czech bakeries and heritage. Kelly Kistner, the Texas assistant state fire marshal, said the fire caused stored ammonium nitrate to change states, while also causing debris in the wooden building to begin to fall.
The blast was actually two explosions: a small one that occurred about 20 minutes after the fire was reported, followed by a larger one a split second later, Kistner said. About 28 to 34 tons of ammonium nitrate stored in the plant exploded. Another 20 to 30 tons stored on site, along with a rail car carrying 100 tons of ammonium nitrate, did not explode, officials said.
The power of the blast was equivalent to 15,000 to 20,000 pounds of dynamite.
Among the dead were 10 first responders and two people who had joined in to fight the fire. The blast registered as a small earthquake and left a crater 93 feet wide and 10 feet deep. It destroyed an apartment building, homes and parts of schools nearby.