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Home » Wyoming National Guard Responds to Unidentified Substance in Gillette, Wyo.

Wyoming National Guard Responds to Unidentified Substance in Gillette, Wyo.

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GILLETTE, Wyo. – Wyoming National Guard responds to an incident involving a suspicious letter with white powder in it and a note indicating exposure to a hazardous substance at the Campbell County Courthouse in Gillette, Wyoming, April 30, 2024.

The 84th Civil Support Team tested the white powder using a range of specialized equipment to test for hazardous materials and determined it posed no danger.

Reflecting on this incident and the partnered response with the 84th CST, JR Fox, the Deputy Chief of Operations for the Campbell County Fire Department and a member of the Regional Emergency Response Team #1 said, “The technical expertise and ability to seamlessly integrate into incident operations make the 84th Civil Support Team a tremendous asset to all communities in Wyoming.”

The incident started when the county attorney’s office received a letter with a potentially hazardous substance. The Campbell County Emergency Management team quickly initiated emergency protocols contacting the Wyoming Office of Homeland Security to seek support from the WYNG’s 84th CST.

The 84th CST, comprised of a 16-member team of Soldiers and Airmen, mobilized and coordinated directly with the emergency manager in Gillette. Upon arrival at the site, the 84th CST began operations using specialized equipment, including handheld assays, explosive testing equipment, radiation testing equipment, and equipment within a mobile lab.

As of the latest update, the initial tests were conducted using handheld assays and mobile lab equipment (Polymerase Chain Reaction (PCR), Gas Chromatograph Mass Spectrometry (GCMS), and Fourier Transform Infrared spectroscopy (FTIR)), which returned negative results for chemical and biological warfare agents. Further confirmation tests were conducted at the State Lab to ensure comprehensive analysis. The State Lab ran tests on the sample using Time Resolved Fluorescence (TRF) and Polymerase Chain Reaction (PCR) then the substance was plated and no growth was observed. Taken together, the State Lab’s results give further confirmation of a negative result for biological agent.

The 84th CST has determined the substance does not pose a threat of chemical or biological warfare or any dangerous implications.

“We are extremely proud of the team’s rapid response supporting our state partners in this potentially dangerous situation. Our team is committed to protecting our fellow Wyoming residents in circumstances just like this.” said Maj. Gen. Greg Porter, Wyoming Adjutant General.

For more information, please contact the Wyoming National Guard Public Affairs at or 307-772-5040.