Ukraine said on Monday it had hit a Russian oil refinery and a microchip factory in a major drone attack that set off fires in the refinery's production facilities and an oil pumping station, Reuters reported.
Hours earlier, Russia said its forces had repelled a nighttime drone attack, but four sources confirmed to Reuters that one of Russia's oldest refineries, the one in the city of Ryazan, had been hit overnight.
The attack set off fires in oil storage facilities at the refinery and damaged equipment including a rail freight facility and equipment for removing impurities from refined products.
A video posted on social media shows smoke and flames engulfing the Ryazan oil refinery and people apparently running to safety in panic. Reuters was able to confirm where the recording was made, but not when.
Pavel Malkov, the governor of Ryazan region, said on Telegram that emergency services were dealing with the aftermath of the Ukrainian attack.
The overnight drone strike appeared to be one of Kiev's largest since the war, Reuters reported.
Russia's Defense Ministry said 20 Ukrainian drones were targeted in the Ryazan region in the attack, which involved a total of 121 drones flying to targets in 13 regions, including Moscow, Reuters reported.
The Ukrainian military said it also struck the "Kremniy EL" microchip plant in the Bryansk region of Russia, which Kiev says produces components for Russian anti-aircraft missile systems and on-board electronics for fighter jets.
TASS quoted a statement from the plant saying that work there had been suspended after a drone attack and that no one was injured. Some of the production facilities and a warehouse were damaged, and the plant's power supply was cut off.