Russian drones attacked energy facilities in Ukraine's northeastern city of Sumy, the regional authorities said on Wednesday.
No people were injured in the attack based on preliminary information but repeated strikes on the region's energy facilities have strained the system, according to the statement on the Telegram messaging app.
Regional authorities said that air defenses shot down 16 drones over the Sumy region during the overnight attack.
The local officials said on Tuesday that Russia fired missiles at energy infrastructure in the city of Sumy after an overnight drone strike on the region reduced power in some areas and forced authorities to use back-up power systems.
Ukraine's energy ministry said Russia's Tuesday attacks had caused a fire at a power substation in the Sumy region and cut power to more than 281,000 consumers. Power was later partially restored, it said.