A building used by Russia’s Federal Security Service has caught fire in the southern city of Rostov, about 40 miles from the border with Ukraine.
Russian state media, citing local emergency services, reported that one person had died and two were injured.
The building belonged to the regional border patrol section of the Federal Security Service, or FSB, the media reports said.
Footage on social media appeared to show fire engulfing parts of the building, with plumes of thick smoke rising over the city.
Regional governor Vasily Golubev said an electrical short circuit caused the fire, which in turn “caused containers of fuel and lubricants to explode”.
Citing anonymous police sources, local media had previously reported that the fire was caused by the detonation of ammunition in a warehouse.