It is reported that the helicopter circled, presumably, over the military unit, after which the sounds of explosions were heard.
Local residents write about the fire in the specified area, special services are working at the scene.
There has been no official comment regarding the incident yet.
The authorities of the Bryansk region previously extended the high, "yellow", level of terrorist threat in the region from May 24 for another 15 days.
The head of Crimea, Sergei Aksyonov, also announced the extension of a high level of terrorist threat on the peninsula, it will be valid until 20:00 on June 25.