A Russian missile strike on Ukraine's capital Kyiv has left three people dead, including one girl, marring celebrations of the country's Children's Day.

Ukrainian police say air defenses intercepted all Russian missiles used in the attack on Thursday. But they add that debris fell into residential neighborhoods, leaving three people dead and at least 14 wounded. They say the dead include a 9-year-old girl and her mother.

Ukrainian prosecutors say Russian forces have killed 484 children and injured 992 since launching their invasion in February of last year. They say these figures are incomplete as it is difficult to gather information from Russian-occupied territory and battleground areas.

Meanwhile, the governor of Russia's western region of Belgorod, which borders Ukraine, revealed in a social media post on Thursday that Ukrainian shelling in the town of Shebekino and elsewhere had wounded 10 people.

The Russian defense ministry says its troops repelled three cross-border attacks in the area on Thursday.

Two self-styled anti-Moscow groups -- the Liberty of Russia Legion and the Russian Volunteer Corps -- posted videos on their social media channels, claiming responsibility for the attacks in Belgorod.

In one of the clips, a person believed to be a member of the Liberty of Russia Legion says the group is going to liberate the whole of Russia.

The two groups also say they carried out a cross-border raid in Belgorod last month.