“At about three o’clock in the afternoon, the Russians shelled the village with artillery — one of the shells hit the yard where the children were,” governor Pavlo Kyrylenko said on social media.
The boy was aged 10 and the girl 16.
Earlier Friday, Kyrylenko said a couple had also been killed by Grad rocket fire in the city of Kostyantynivka.
In the Chernigiv region in northern Ukraine, governor Vyacheslav Chaus said an employee of a cultural centre had been found dead after Russian shelling.
In the region of Odesa, southern Ukraine, governor Oleg Kiper said that out of a total of 21 people wounded in a barrage of Russian missile and drone attacks over the past four days, four people were still hospitalised.