The press service of St. Petersburg's city administration said an "incident" occurred at an industrial site in the Nevsky district of the city on Jan. 31, the Russian state-run media outlet TASS reported.
The Ukrainian media outlet RBC Ukraine claimed that a drone had struck the Nevsky Mazut oil refinery in the city. Citing unnamed sources, RBC said that the strike was carried out by Ukraine's military intelligence (HUR).
The sources told RBC Ukraine that Russia had used its S-400 air defense system to target the drone, but it proved ineffective, and the drone fell on its alleged target.
Ukrainska Pravda also said that sources in Ukraine's military intelligence had claimed responsibility for the alleged strike.
The Kyiv Independent reached out to Ukraine's military intelligence for comment, but a spokesperson said he could not confirm its involvement. The claims made by Ukrainska Pravda and RBC Ukraine cannot be independently verified at the time of this publication.
Russian Telegram channels shared videos of the alleged strike and ensuing explosion.
St. Petersburg Governor Alexander Beglov confirmed that an explosion had occurred, which he referred to as an "incident." Beglov said that there were no casualties or significant damage reported.