As stated on the website of the Operational Command of the Branches of the Armed Forces:
On 10 March, employees of the Rad-Min demining company, who were clearing the forested grounds of a former Soviet military training area, found 16 steel barrels containing an unknown chemical substance. Due to the potential threat posed by the discovered storage site, the Lower Silesian Voivode submitted a request to the Minister of National Defence for support to the public administration in a crisis situation. […]
The soldiers thoroughly searched the designated area, as a result of which they found five additional barrels bearing inscriptions in Russian reading “Deadly Poison”. They collected samples of the substance and conducted analyses in the Mobile Chemical Laboratory, while also sending the material for testing at another stationary laboratory to confirm the results obtained. The analyses showed that the barrels contained a mixture of various substances used to simulate chemical contamination, while they ruled out the presence of Chemical Warfare Agents [podkreślenia – „ii”].
The barrels and their contents were placed in airtight containers and transported to the storage facility in Komorowo, where they will be disposed of.
Operational Command of the Branches of the Armed Forces/ii