For the Russians, the Ukrainian fighters held prisoner at Correctional Colony No. 120 are a trophy. For the Ukrainians, they are war heroes.

Why either side would want any of them dead is a mystery, but that is the question that hung over the fighting in Ukraine on Friday after another deadly episode, with each side accusing the other of committing a war crime.

What is known is that an explosion ripped through a barracks of the prison camp in the Russian-occupied town of Olenivka in southeastern Ukraine early Friday morning, killing at least 50 captured fighters and maiming dozens more, according to both Ukrainian and Russian officials. Videos posted by Russian war bloggers show twisted metal bunk beds and the charred bodies of their former occupants.