 The NDH authorities in Trebinje heard rumours that the Serbs could start an uprising there on 28 June , the feast day of Saint <unk> , and warned NDH forces in the region to be prepared for a revolt . As a result of these reports , the <unk> ( leader ) of the NDH , Ante Pavelić , issued orders threatening that anyone who spread these rumours would be court @-@ <unk> . On the eve of the feast day , both the gendarmerie and Ustaše took several hostages in case the rumours were true . Later , the gendarmerie released their hostages , but the 19 hostages held by the Ustaše were killed . In contrast to the actions of the Ustaše , the Home Guard units in the area tried to calm the situation down . 
