KYIV, Ukraine (AP) — Russia-backed separatists in eastern Ukraine say that at least 40 Ukrainian prisoners of war captured during the fighting for Mariupol have been killed by Ukrainian shelling.

Daniil Bezsonov, a spokesman for the Russia-backed separatists in the Donetsk region, said that at least 40 Ukrainian prisoners of war were killed and 130 were injured Friday when Ukrainian shelling hit a prison in the town of Olenivka.

The Ukrainian troops were taken prisoner after the fierce fighting for Ukraine’s Azov Sea port of Mariupol, where they holed up at the giant Azovstal steel mill for months.