Tikvesh uprising  was an uprising in the Tikveš region of Macedonia in late June 1913. It was organized by the Internal Macedonian Revolutionary Organization  against the Serbian government in Vardar Macedonia and took place behind the Serbian lines during the Second Balkan War. IMRO acted in close coordination with the Bulgarian army generals in Macedonia, whose troops at the time were located on the left bank of the Vardar river. The rebellion started prematurely on June 15, 1913, after the secret uprising conspiracy had been revealed by the local Serbian authorities. The organisers had planned to start armed resistance against the oppressors after the Bulgarian Army had begun operations in the region. The rebellion spread in the regions of Kavadarci, Negotino and the village of Vatasha. Two large rebel groups were set up with leaders Doncho Lazarov and Mishe Shkartov. The Serbian army unit in Negotino was attacked and forced out from the town, Kavadarci and Vatasha were liberated soon after. The rebellions set up a provisional Bulgarian government in these settlements. Reorganized Serbian army troops and irregulars led by Vasilije Trbić were sent to crush the uprising. On June 25, after realising that help from the Bulgarian army would not be coming soon, the rebels moved out from the towns. In the following days the Serbian army brutally suppressed the uprising and terrorized the Bulgarian population in the rebelling regions. According to some sources 363 civilians were killed in Kavadarci, 230 - in Negotino and 40 - in Vatasha.
Question: Who killed the civilians in Kavadarci, Negotino, and Vatasha?
Answer: Bulgarian army