At least 600,000 people across Ukraine are now without electricity after deadly overnight Russian missile and drone strikes, President Volodymyr Zelensky has said.
He said "critical" energy infrastructure had been hit in Kyiv and the capital region and also in the north-eastern city of Kharkiv - despite a claim by US President Donald Trump on Sunday that an "energy ceasefire" was in place between Russia and Ukraine.
In Kyiv, at least three people were killed and 21 injured, Ukraine's state emergencies service DSNS said.
Russia's defence ministry said its "massive" strikes overnight had targeted communications and energy facilities in the Kyiv and Kharkiv regions used by Ukraine's military.
The defence ministry also said 902 Ukrainian drones had been shot down overnight over a number of Russian regions, including the capital Moscow and Crimea - Ukraine's southern peninsula annexed by Russia in 2014.
Ukraine's air force said that overnight, Russia had launched 39 ballistic and cruise missiles and 128 drones, and that four of those missiles and 115 drones had been shot down.
On Sunday, Trump wrote in a post on social media: "Effective immediately, there is an ENERGY CEASEFIRE in the War between Russia and Ukraine. Both parties have agreed. Do not break it!"
President Zelensky has since repeatedly said Ukraine is ready to halt its strikes on Russian oil refineries and other energy facilities if Moscow did the same.
But Russia's Foreign Minister Sergey Lavrov has said Ukraine does not deserve the "respite" a ceasefire would bring. Under any truce, he added, Europe would be able to "pump [Ukraine] with new weapons" for it to continue the war.
Russian President Vladimir Putin launched a full-scale invasion of Ukraine in 2022, and Moscow currently controls about 20% of Ukrainian territory.