Ukraine's President Volodymyr Zelenskyy has accused Russia of killing seven people including three children in a drone attack in the eastern city of Kharkiv.

The attack on Ukraine's second-largest city took place Friday through Saturday, hitting an oil storage facility. The victims, including the children's parents, died in a fire caused by leaked fuel.

Police released footage showing police officers entering burning residential buildings and rescuing people.

Zelenskyy remembered the dead in his social media post on Saturday, citing the names of the three children.

He said "Russian terror" cannot remain unpunished. He demanded Russia take responsibility for every life it destroyed.

International human rights organization Human Rights Watch said in its report on Thursday that at least 8,000 people in Mariupol have likely died in Russia's invasion. Russia took control of the city in Ukraine's east region of Donetsk in May 2022 after fierce fighting.

The estimation is based on the group's analysis of satellite imagery of major cemeteries. It said the full extent of those who died during the battle may never be known as these figures are likely a significant underestimation of the total number of dead.

Ukraine says more than 20,000 of Mariupol's population of about 400,000 have been killed in Russia's invasion. Casualty details have not been reported as the city is under Russia's control.

Kremlin spokesperson Dmitry Peskov was asked about the Human Rights Watch report Friday. He said he cannot tell how reliable it is before he reads it. He said Ukrainian forces used civilians as human shields and shot them from behind.