Scores of state and federal investigators continue to search for clues to what led to a massive explosion at a West fertilizer plant, killing 15 — including a 96-year-old man who died in the hours following the blast — injuring about 200 and leaving a 93-foot-wide, 10-foot-deep crater in its wake, officials said Tuesday afternoon.
“This is much like an archeological dig we are going through, as we go through this fire scene,” said Kelly Kistner, assistant state fire marshal. “There are over 70 agents, state and federal, that are on the ground out there … going through this blast scene.”
Authorities are trying to identify the heat source that started the fire, and what material first ignited. Once determined, investigators will be able to classify the blaze as accidental or incendiary — or, if never found, undetermined.
Officials have ruled out a natural cause to the fire, such as a lightning strike, Kistner said.
Using blast patterns and evidence analysis, investigators have also determined that a railcar filled with ammonium nitrate “is not the cause of the fire or the cause of the explosion,” Kistner said.
“It is a victim of the explosion,” he said.
On Monday alone, investigators interviewed as many as 70 people, Kistner added.
Authorities are still inventorying the materials that were at the plant at the time of the explosion and the materials that remain there now.
The amounts at the site do not pose a hazard, Kistner said.
“Most of those have been mitigated, but we do have other agencies that are right there that are monitoring those situations for us,” said Robert Champion, special agent in charge from the Dallas division of the Bureau of Alcohol, Tobacco, Firearms and Explosives.
Both the State Fire Marshal’s Office and the ATF are investigating the fire and explosion. Authorities have also called in fire protection engineers.
West Mayor Pro Tem Steve Vanek said at a press conference Tuesday afternoon that all houses and buildings in the area of the blast have been cleared and officials do not expect to find any more bodies of people killed by the explosion.