After Lviv was occupied by the Nazi Germany in June 1941, the Germans closed the University of Ivan Franko and killed over 20 Polish professors (as well as members of their households and guests, increasing the total number of victims to above forty). The victims included lecturers from the University of Lviv and other local academic institutions. Among the killed was the last rector of the University of Jan Kazimierz, Roman Longchamps de Berier, his three sons, and the former Polish prime minister and a polytechnic professor, Kazimierz Bartel. The underground University of Jan Kazimierz was established in Autumn 1941.