Videos of the incident shared on local public channels show damage to the alleged FSB building, with fire and smoke visible in the footage.
Local residents also reported damage to a two-story building.
Krymskyy Veter (Crimean Wind), a local public Telegram channel, reported explosions in Armyansk at 10:30 p.m.
On April 5, explosions also rocked Simferopol and Bakhchysarai in Crimea.
Local telegram channels reported strikes on Kacha airfield and Sevastopol.
Strikes were also reported between Simferopol and Bakhchysarai near Russian military training grounds.
On May 5, Ukraine's Defense Intelligence announced that it struck a Beriev Be-12 Chayka amphibious patrol aircraft, three assault boats, and a Russian military supply vessel in Crimea.
On May 2, Ukrainian Defense Forces conducted a series of successful strikes on Russian military targets, hitting a tactical group of Iskander short-range ballistic missile systems in Crimea. The attack also took out two key radar complexes: a Mys-M1 coastal radar station (Mayak) and a Podlyot radar station in Yevpatoria.