According to the paper “Bulgaria and Hungary in the First World War: A View from the 21st Century”, published in 2020, the following can be read:

“In early October of 1913, in pursuit of attacking Albanian forces, the Serbian army again crossed the borders established in London, and within two weeks had occupied a significant portion of northern and central Albania. In order to assure themselves of a permanent military presence, they busied themselves building a system of fortresses at strategic points throughout these occupied territories; according to Austro-Hungarian and Bulgarian sources, close to 25,000 civilians lost their lives in the course of this most recent occupation of Albania. Most of these people were slaughtered along the
banks of the Black Drin so as to create a cordon sanitaire along the Serbian–Albanian border”.

Reference: “Bulgaria and Hungary in the First World War: A View from the 21st Century”. 2020. Demetar Bolgar. Editors: Pal Fodor, Gabor Demeter, Csaba Katona, Penka Peykovska. p. 61.