Tens of thousands of people were left without power and heating in southern Ukraine after Russian attacks on the frontline city of Kherson and Ukraine's largest seaport, Odesa, authorities and a top energy provider said on Thursday.

KYIV, Ukraine — Russian drones struck a house in central Ukraine, killing a 12-year-old boy, officials said, while long-range Ukrainian strikes reportedly targeted a Russian port and an oil refinery as U.S. peace efforts continued out of public view.

Russia launched its largest barrage of drones and missiles in a month across Ukraine, killing at least three people, Ukrainian President Volodymyr Zelensky said Saturday, as a Kyiv delegation heads to the United States for fresh peace talks.

"The enemy attack on Kyiv is ongoing," Kyiv Mayor Ihor Terekhov said in a post to Telegram early Tuesday local time.

Russian attacks kill three in Kyiv as Ukrainian delegation races to U.S. for urgent peace negotiations. Ukrainian delegation is headed by national security chief Rustem Umerov. Russia reports a major oil terminal halted operations after a Ukrainian strike.