Russian forces launched a series of overnight strikes that have knocked out power supplies in parts of Kharkiv, Ukraine's second city, local officials said on Friday.
There was no word on casualties.
"The occupiers hit critical infrastructure. There were about 10 explosions," Kharkiv governor Oleh Synehubov said on Telegram. "In some regions, there are power cuts. Emergency services are on site."
Kharkiv Mayor Ihor Terekhov said the 4 a.m. strikes could disrupt power, heating and water supplies.