Cause of Texas fertilizer plant blast 'undetermined'
The cause of a deadly explosion at a fertilizer plant that destroyed much of West, Texas remains "undetermined" but officials said Thursday a criminal investigation will continue.
"An undetermined cause occurs when the cause cannot be proven to an acceptable level of certainty," State Fire Marshal Chris Connealy told reporters.
Three potential causes have not yet been eliminated: a malfunction in the plant's electrical system, a golf cart that could have malfunctioned and sparked a fire, and an intentionally set fire.
A local paramedic was recently arrested on charges of possessing the materials to build a pipe bomb, but investigators would not confirm whether he was a suspect in the deadly blast.
"At this time, authorities will not speculate as to whether the possession of that explosive device had any connection to the West fertilizer plant explosion," said Robert Champion, special agent in charge of the Dallas office of the Bureau of Alcohol, Tobacco, Firearms and Explosives.
Some 15 people -- including a dozen firefighters -- were killed and 200 were injured in the April 17 blast which was so powerful it registered as a 2.1-magnitude earthquake.
"The tragedy in West has dramatically changed the lives of many in this tight-knit community, forever leaving its mark on the town and in the hearts of those who call West home," Texas Governor Rick Perry said in a statement.
"While the cause of the fire remains undetermined and the investigation continues, this tragedy has shown the world the definition of compassion, from volunteer firefighters across the state rushing to help their colleagues at the scene, to friends, neighbors and Texans stepping in to help those who lost so much in the blast."
The explosion caused damage in a 37-block area of the town of just 2,800 people, leaving a crater that was 93 feet (28 meters) wide and 10 feet deep.
Debris was found up to 2.5 miles (four kilometers) away.
Homes near the blast site were flattened, a huge apartment complex was destroyed and a nursing home and several schools were also badly damaged by fire that spread from building to building following the explosion.
Investigators determined that the between 28 and 34 tones of ammonium nitrate exploded in two blasts which were just milliseconds apart and were caused by the heat of the fire and the impact of falling debris.
Thankfully, an additional 20 to 30 tones of the fertilizer that was in the building did not explode, nor did 100 tones of ammonium nitrate that was stored in a rail car that was also damaged by the blast.
The blast was equivalent to about 15,000 to 20,000 pounds of the explosive TNT, or Trinitrotoluene, investigators said.