As many as 13 people are missing in the Kherson region, Interior Minister Ihor Klymenko said
Russia's defence ministry said Ukraine struck a prison in separatist-held territory with US-made HIMARS rockets on Friday, killing 40 Ukrainian prisoners of war and leaving 75 wounded.
Battlefield reports could not be immediately verified.
"A missile strike from the US-made multiple launch rocket system (HIMARS) was carried out on a pre-trial detention center in the area of the settlement of Olenivka, where Ukrainian military prisoners of war, including fighters from the Azov battalion, are being held," the defence ministry said in its daily briefing.
As a result of the strike, "40 Ukrainian prisoners of war were killed and 75 wounded," and eight prison staff were also injured, it added.