Russia and Ukraine launched air attacks damaging each other's infrastructure after Russian President Vladimir Putin rejected a 30-day ceasefire proposal from the US.
Ukrainian President Volodymyr Zelensky accused Russia of targeting "civilian infrastructure" overnight, including a hospital in Sumy.
Putin had agreed to a 30-day pause in strikes on energy infrastructure during a call with Donald Trump on Tuesday but declined a broader ceasefire.
Talks on Ukraine are set to continue on Sunday in Saudi Arabia, according to US envoy Steve Witkoff.
During the call, Putin and Trump also agreed to a prisoner swap, with 175 detainees from each side expected to be exchanged today.
