The bodies were found in a five-story building that collapsed in March in Izyum, about 120km from the city of Kharkiv, which has been under sustained Russian attack since the beginning of the war in late February.
"This is another horrible war crime of the Russian occupiers against the civilian population!" said Oleh Synehubov, the head of the regional administration, in a social media message announcing the deaths.
Amnesty International has obtained evidence that civilians were killed in indiscriminate attacks in Kharkiv and Sumy Oblast, documented an airstrike that killed civilians queueing for food in Chernihiv, and gathered evidence from civilians living under siege in Kharkiv, Izium and Mariupol.
Bucha’s mayor estimates that 20% of the city’s population was killed during Russian occupation, with widespread reports of mass murder, rape and torture of civilians.