One person was killed, and several apartments and an industrial facility were damaged in a Ukrainian drone attack on the south Russian region of Saratov, the governor said on Sunday.

Roman Busargin posted on the Telegram messaging app that residents were evacuated after debris from a destroyed drone damaged three apartments in the overnight attack.

"Several residents required medical assistance," Busargin said. "Aid was provided onsite, and one person has been hospitalised. Unfortunately, one person has died."

Busargin did not specify what kind of industrial site was damaged.

Social media footage showed thick black smoke rising over what looked like an industrial zone. Reuters verified the location seen in one of the videos as matching file and satellite imagery of the area. Reuters could not verify when the video was filmed.

Ukrainian media, including the RBK-Ukraine media outlet, reported that the oil refinery in the city of Saratov, the administrative centre of the region, was on fire after a drone attack.

Flights halted over Saratov

The Rosneft-owned refinery in the Saratov city was forced to suspend operations earlier this year for safety reasons after Ukrainian drone attacks, industry sources told Reuters.

Russia's SHOT Telegram channel, which often publishes information from sources in the security services and law enforcement, reported about eight explosions were heard over Saratov and Engels, cities separated by the Volga River.

Russia's civil aviation authority Rosaviatsia said on Telegram that flights in and out of Saratov had been halted for about two hours early on Sunday to ensure air safety.

Both sides deny targeting civilians in their strikes on each other's territory in the war that Russia launched its military campaign in Ukraine in February 2022.

Kiev says its attacks inside Russia are aimed at destroying infrastructure that is key to Moscow's war efforts, including energy and military infrastructure, and are in response to Russia's continued strikes.