The West Fertilizer plant where at least five were killed last night failed to obtain a permit for operation in 2006, according to the Texas Commission on Environmental Quality. Complaints of ammonia propelled an investigation by the agency, which concluded that an impact on local schools and residencies was low.
The explosion occurred just two days before the 20th anniversary of another local fire, which resulted in the deaths of a Branch Davidian sect.
Though the cause of the explosion is still unknown, the combination of ammonia nitrate with water could have caused an explosion similar to the Oklahoma City Bombing, where ammonium nitrate fertilizer was used as an explosive.
As much as 54,000 pounds anhydrous ammonia (which is used to make low cost fertilizer) was found stored inside the factory. Even slight exposure to the chemical can cause blisters and burns, requiring large quantities of water for recovery.
Authorities continue to evacuate homes, though wind forecasts suggest the entire town may be evacuated in expectation of exposure.