A massive Ukrainian drone attack on Crimea early Friday caused power cutoffs in the city of Sevastopol and set a refinery ablaze in southern Russia, Russian authorities said. The drone raids marked an attempt to strike back during Moscow"s renewed offensive in northeastern Ukraine, which has added to the pressure on outnumbered and outgunned Ukrainian forces as they await delayed deliveries of crucial Western weapons and ammunition. Ukraine has not commented on the attack nor claimed responsibility for it. The Russian Defence Ministry said its air defenses downed 51 Ukrainian drones over Crimea, another 44 over the Krasnodar region and six over the Belgorod region. It also said Russian warplanes and patrol boats had destroyed six sea drones in the Black Sea. Moscow"s claims could not be independently verified. Mikhail Razvozhayev, the Moscow-appointed governor of Sevastopol, which is the main base for Russia"s Black Sea Fleet, said the drone attack damaged the city"s power plant. He said it could take a day to fully restore energy supplies and warned residents that power would be cut to parts of the city. "Communal services are doing their best to restore the power system as quickly as possible," he said in a statement. Razvozhayev also announced that schools in the city would be closed temporarily. Earlier Ukrainian attacks damaged aircraft and a fuel storage facility at Belbek air base near Sevastopol, according to satellite images released by Maxar Technologies. In the Krasnodar region, the authorities said a drone attack early Friday caused a fire at an oil refinery in Tuapse, which was later contained. There were no casualties. Ukraine has long been targeting refineries and other energy facilities deeper inside Russia, causing significant damage in an attempt to make the consequences of the invasion felt by everyday Russians. Ukrainian drones also attacked Novorossiysk, a major Black Sea port. The Krasnodar region"s governor, Veniamin Kondratyev, said fragments of downed drones caused several fires, but there were no casualties. Belgorov Governor Vyacheslav Gladkov said a Ukrainian drone struck a vehicle, killing a woman and her 4-year-old child. Another attack set a fuel tank ablaze at a gas station in the region, he said. Meanwhile, Ukrainian troops were fighting to halt Russian advances in the northeastern Kharkiv region that began late last week. The town of Vovchansk, located just 5km from the Russian border, has been a hot spot in the recent fighting, and Ukrainian authorities have evacuated some 8,000 civilians from the town. A common tactic of the Russian army is to reduce towns and villages to ruins with aerial strikes before its units move in. Russia has also been testing defenses at other points along the roughly 1,000-kilometre front line that snakes from north to south through eastern Ukraine. That line has barely changed over the past 18 months in what became a war of attrition. Recent Russian attacks have come in the eastern Donetsk region, as well as the Chernihiv and Sumy regions in the north and the southern Zaporizhzhia region. The apparent aim is to stretch depleted Ukrainian resources and exploit weaknesses. — Euronews