Around 60,000 pounds of a substance called ammonium nitrate vanished during transportation by rail from Wyoming to California recently. This material has the dual use of being a fertilizer and a component in explosives, and its disappearance has prompted four independent investigations.

On April 12, a rail car containing 30 tons of a chemical departed from Cheyenne, Wyoming. Two weeks later, when it arrived at its destination rail stop in the Mojave Desert, the explosives company responsible for the shipment reported that the rail car was found to be completely empty.

On May 10th, Dyno Nobel reported to the National Response Center (NRC), and this report was later added to a California incident database managed by the state Office of Emergency Services on the following Wednesday.

Ammonium nitrate is a commonly used fertilizer that can also be utilized as a key component in high explosives. In fact, it was one of the components in the homemade bomb that was detonated in the Murrah Federal Building attack in Oklahoma City back in 1995.

Dyno Nobel reports that it assumes that the substance, which was being transported in the form of pellets inside a covered railway car similar to the ones utilized for coal shipment, fell out while en route to a railroad siding called Saltdale, around 30 miles from the town of Mojave in eastern Kern County.

According to a spokesperson for the company, the rail car was initially sealed when it departed from the Cheyenne facility and remained sealed until it arrived in Saltdale. However, it is believed that there may have been a leakage issue through the bottom gate of the rail car during transportation.

A spokesperson from the Federal Railroad Administration, has said that the investigation indicates that one of the gates on the hopper car was not correctly shut.

Dyno Nobel, says that the recent trip involved several stops and lasted two weeks, during which the company claims it had limited control over, as it was transported by Union Pacific across the country. The railcar is now being returned to Wyoming for inspection.

Dyno Nobel says it hopes to gain insight into how the shipment was lost and will take preventative measures to avoid a recurrence in the future.

Representatives from the California Public Utilities Commission, Union Pacific, Dyno Nobel and the Federal Railroad Administration are currently conducting an investigation into the incident.

In 2007, a law was passed by Congress to oversee the sales and transfers of ammonium nitrate, aimed at preventing its use in terrorist activities. The Department of Homeland Security proposed regulations in 2011 but did not officially implement them.