Russia and Ukraine exchanged massive attacks early on Sunday that left smoke rising from the roof of Kyiv's cabinet of ministers building.
At least four people, including a two-month-old child, were killed in the Ukrainian capital after a large Russian drone and missile attack.
Several buildings were set on fire, including the seat of the government in the city centre, Kyiv Mayor Vitali Klitschko said.
“The roof and upper floors were damaged due to an enemy attack. Rescuers are extinguishing the fire,” Ukrainian Prime Minister Yulia Svyrydenko posted on Telegram.
Ukraine's air force said Russia launched 805 drones and 13 missiles on the country overnight.
Russian air defence units destroyed 69 Ukrainian drones overnight, RIA news agency reported on Sunday.
Ukraine said it attacked the Druzhba oil pipeline in Russia's Bryansk region. Commander of Ukraine's drone forces, Robert Brovdi, said a “comprehensive fire damage” had been inflicted on the pipeline that transits Russian oil to Hungary and Slovakia.
The barrage came after two dozen countries, led by France and Britain, pledged on Thursday to join a “reassurance” force to patrol any agreement to end the war, unleashed by Moscow's February 2022 invasion.
Kyiv says security guarantees, backed by western troops, are crucial to any peace deal to ensure Russia does not invade again in the future.
However, Russian President Vladimir Putin has dismissed any western forces in Ukraine as unacceptable and said they would be “legitimate” targets.
Efforts in recent weeks by US President Donald Trump to end the war have so far yielded little progress.
