60,000 pounds of ammonium nitrate went missing; leaky train car is current explanation

Via KQED: 

Some 60,000 pounds of ammonium nitrate, a chemical used as both fertilizer and a component in explosives, went missing as it was shipped by rail from Wyoming to California last month, prompting four separate investigations.

A railcar loaded with 30 tons of the chemical left Cheyenne, Wyoming, on April 12. The car was found to be empty after it arrived two weeks later at a rail stop in the Mojave Desert, according to a short incident report from the explosives firm that made the shipment.

The company, Dyno Nobel, made the report May 10 to the federal National Response Center, or NRC. The report also appeared last week in an NRC database of California incidents managed by the state Office of Emergency Services last Wednesday.

There appears to be an innocent explanation: 

Dyno Nobel says it believes the material — transported in pellet form in a covered hopper car similar to those used to ship coal — fell from the car on the way to a rail siding (a short track connecting with the main track) called Saltdale about 30 miles from the town of Mojave in eastern Kern County.

“The railcar was sealed when it left the Cheyenne facility, and the seals were still intact when it arrived in Saltdale. The initial assessment is that a leak through the bottom gate on the railcar may have developed in transit,” the company said through a spokesperson.

A Federal Railroad Administration representative, though, says the investigation points to one of the hopper car gates not being properly closed.

Here's hoping this simple explanation is the correct one, and that this material is not actively being mixed with fuel oil.