Earlier, Russian forces shot and killed 10 people queuing for bread in Chernihiv, northern Ukraine, the US embassy in Kyiv has said.
"We are considering all available options to ensure accountability for any atrocity crimes in Ukraine.".
Please use Chrome browser for a more accessible video player 1:17 'Half of my leg was torn away'.
Earlier, Ukrainian presidential adviser Mykhailo Podolyak said a "radical change" had occurred between Ukrainian and Russian forces after Kyiv launched counteroffensives in "several operational areas".
The UK Ministry of Defence, meanwhile, has said Ukraine is "adeptly exploiting" Russian forces' "lack of manoeuvre" and inflicting heavy losses.
"The tactics of the Ukrainian armed forces have adeptly exploited Russia's lack of manoeuvre, frustrating the Russian advance and inflicting heavy losses on the invading forces.".
Russian forces have struck more than 400 educational establishments and 59 of them have been destroyed, Iryna Venediktova said on Facebook. »