Ukraine is switching to emergency shutdowns to stabilise its power grid after a fresh wave of Russian missile attacks hit the country on Monday.
President Volodymyr Zelensky said many regions were affected, and officials said half of the Kyiv region would go without electricity in the coming days.
Four people were killed in Monday’s attacks on Ukraine’s infrastructure.
And overnight more missiles hit critical facilities near the southern city of Zaporizhzhia, officials said.
In a separate development on Tuesday, the governor of Russia’s Kursk region said a drone attack on an airfield set an oil storage tank alight. Videos showed fierce flames and dense black smoke billowing from the site.
That came after a series of explosions at two military airfields deep inside Russia on Monday, which Moscow blamed on Ukrainian drones.
In Ukraine, the energy minister said he hoped to significantly reduce the power deficit caused by the latest Russian strikes by bringing nuclear power stations back onto the grid.
The country is now seeing snow and sub-zero temperatures in many regions, and millions are without electricity and running water, raising fears people may die of hypothermia.
Marina, a resident of Vyshgorod, in the Kyiv region told the BBC how she gathers with her husband and children in one room to keep warm during scheduled power outages.
“We turn on electric heaters and warm up the room well, and then we are all in this room together, without opening the door. We have enough heat for four hours,” the 39-year-old said.
She described how she tries to do everything she can while the lights are working, as they can go out for long periods.