Myhailo Podoliak, a senior adviser to Ukrainian President Volodymyr Zelensky, said early Saturday that Russian forces had tried to "bring the maximum amount of equipment into the city of Kyiv."

But, he said, "Currently, the situation in the suburbs and the surrounding area is under control."

Speaking on Ukrainian television, he said there were "separate sabotage and reconnaissance groups" in the city, but that police and territorial self-defense units "are actively working against them."

Battle in the city: Earlier Saturday, the Ukrainian Interior Ministry warned Kyiv residents that fighting was taking place on the streets, and urged civilians to seek shelter and stay indoors. Gunfire was heard near the city center before dawn, following several hours of loud explosions in and around the capital.