Russian strikes left hundreds of thousands of Ukrainians without power on Sunday, President Volodymyr Zelenskiy said, while Russian authorities reported major damage to an industrial site following Ukrainian drone attacks on Nizhny Novgorod region. Even as a six-day local ceasefire held on its final day around the Russian-controlled Ukrainian town of Oleshky, there was no letup in fighting elsewhere along the front line and both sides kept up long-range air attacks. Zelenskiy said Russia had hit power infrastructure in four Ukrainian regions overnight, cutting electricity to hundreds of thousands of households. "The intensity of the strikes is very high, and the Russians are seeking to maximally exploit the deficit of ballistic missile interceptors," he said on Telegram. He said Ukraine, meanwhile, had hit the Kamensky plant in Russia's Rostov region, which he said was involved in the manufacture of Russian missiles. Moscow did not comment on the reported attack in Rostov. Read: Trump says Russia-Ukraine deal could be near ahead of December’s G20 summit In Nizhny Novgorod region, however, Governor Gleb Nikitin said a large-scale overnight Ukrainian drone attack caused "significant damage" to an industrial facility. He did not identify the site that was hit. The region is home to the NORSI oil refinery, one of Russia's largest. Overall, Russia's Defence Ministry said its forces had downed 235 Ukrainian drones over Russian regions overnight. Ukraine's air force said it had shot down 371 of 433 long-range drones launched by Russia since Saturday evening. In its morning update, the air force said dozens of Russian drones were still in the air as of Sunday morning. Six separate drone alerts had been issued in Kyiv since midnight. Fuel supplies Nizhny Novgorod's regional government also did not identify the facility that was struck, but it said it was taking steps to ensure gas stations were supplied with fuel, urging motorists to "buy fuel only as needed and avoid panic buying," Interfax reported. The warning suggests the damaged facility was linked to the region's oil-refining or fuel-supply infrastructure. Kyiv did not immediately claim responsibility for the Nizhny Novgorod attack. Read More: US approves $2.1 billion Patriot missile sale to Ukraine On Friday, Russia said Ukraine had resumed strikes on its oil refineries and accused Kyiv of ignoring a request from US President Donald Trump to stop such attacks, which Trump has blamed for raising the cost of diesel before US midterm elections next week. Ukraine says it supports a full ceasefire on energy targets, including its own battered power grid, but that Moscow is unwilling to agree to this. In an interview with state TV channel Vesti on Sunday, Russian Deputy Prime Minister Alexander Novak, who oversees the energy sector, did not mention the Nizhny Novgorod strike, but said Ukrainian strikes on Russian refineries were adding to global fuel market imbalances and affecting prices.