About 60 people were feared dead after a bomb struck a school in eastern Ukraine, authorities said, while Russian President Vladimir Putin prepared to lead celebrations on Monday marking the Soviet Union's victory over Nazi Germany in World War II.

Luhansk region Gov. Serhiy Gaidai said the school in Bilohorivka, where about 90 people were sheltering, was hit on Saturday by a Russian bomb, setting it ablaze.

"There is almost no hope that anyone survived. The aerial bomb exploded in the middle (of the building)," Gaidai wrote on the Telegram messaging app. "In the school, there were approximately 90 people, 27 were rescued. About 60 people were probably killed."