Ukraine attacked an oil refinery in Russia’s Kaluga region with drones on Friday morning, causing damage, in an operation led by the Military Intelligence Service (MIS), a Ukrainian intelligence source told Reuters.

Ukraine is checking the extent of the damage, the source said. Reuters said it could not independently verify the information.

Earlier, the governor of the Kaluga region, Vladyslav Sapsa, reported on Telegram that air defense shot down four drones in the area of ​​the oil refinery, there were no damage to the infrastructure, and no casualties.

Photos, which were initially published on Russian channels and show the moment of the impact on the refinery, are circulating on social networks.