That's a tough loss for a country at war with its neighbour:

Interior Minister Denys Monastyrsky, responsible for the police and security inside Ukraine, would be the most senior Ukrainian official to die since the war began.
National police chief Ihor Klymenko said Interior Minister Denys Monastyrskyi had been killed alongside his first deputy, Yevheniy Yenin, and other officials in a helicopter belonging to the state emergency service.

Edit: included another quote