Approximately 61,000 pounds of ammonium nitrate, a chemical used as both fertilizer and an ingredient in explosives, went missing when it was shipped by rail from Wyoming to California last month, prompting officials to begin investigating the mysterious disappearance. 

Ammonium nitrate was used in 1995 at an attack on the Murrah Federal Building in Oklahoma City. The explosion killed 168 people and injured approximately 850.

On April 12, a railcar loaded with 30 tons of the chemical left Cheyenne, Wyoming. However, according to an incident report from Dyno Nobel, when the car arrived two weeks later at a rail stop in the Mojave Desert, it was completely empty. 

Dyno Nobel, the company responsible for shipping the ammonium nitrate is a leader in commercial explosives and filed a report with the federal National Response Center (NRC) on May 10.

The Federal Railroad Administration, the California Public Utilities Commission, Union Pacific, and Dyno Nobel are looking into the disappearance, and the railcar is being transported back to Wyoming to undergo a thorough inspection.

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Dyno Nobel told local station KQED News that they believe that the material fell from the car on the way to a rail siding about 30 miles from Mojave.

"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 told KQED News.

Dyno Nobel did not immediately respond to Fox News Digital's request for comment but told local outlets that the railcar had made multiple stops on its journey and that there is a team working to investigate how the supposed leak occurred. 

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"We take this matter seriously and will work to understand how it happened and how it can be prevented from occurring again," a spokesperson told KQED.