Ukrainian drones hit a Russian oil refinery in the city of Ryazan overnight, causing a fire and damaging equipment at one of Russia's biggest refineries, four industry sources told Reuters on Friday.

Kyiv on Sunday claimed responsibility for an overnight drone attack on a Russian oil refinery, making it the second attack on the same site in less than two weeks. Ukraine's military said that "the Defense Intelligence of Ukraine hit the facilities of the Ryazan Oil Refining Company again.

During the night from Saturday to Sunday, foreign drones—most likely Ukrainian—appeared over the refinery in the city of Ryazan, located about 125 miles southeast of Moscow. A series of explosions occurred.

Video footage taken on Jan. 23 shows an alleged drone attack conducted by Ukrainian armed forces attacking the Rostneft Oil Refinery in Ryazan, Russia by using many long-range kamikaze drones.

Ukraine drones hit an oil refinery east of Moscow in a mass attack on Russia, according to military sources. The oil plant in Ryazan, 120 miles south east of the capital, was targeted, as was a microelectronics production plant in Bryansk, western Russia, according to Ukraine’s military.

Emergency crews in Russia’s Ryazan region are responding to an early morning drone attack. Governor Pavel Malkov reported that air defense units intercepted drones targeting the main town. Unverified videos on Telegram suggest major fires,

The Ryazan Oil Refinery in Russia has suspended operations due to damage from Ukrainian drone attacks, Reuters reported on Jan. 27, citing two industry sources. Ukraine confirmed hitting the plant in an overnight drone strike on Jan.

The Ryazan oil refinery, one of Russia's largest refineries, has temporarily halted operations following strikes by Ukrainian forces, Reuters reports. Unnamed industry sources told Reuters that an oil storage facility at the plant was set on fire.