At least 17 people were killed in clashes between security forces and Ethiopian activists seeking new autonomous areas for their Sidama ethnic group, according to local officials and the hospital.
A local district official told Reuters news agency on Saturday that at least 13 people were killed in a town near the town of Hawassa, 275 kilometers south of the capital Addis Ababa, while hospital authorities said on Friday that four protesters had been killed in gunshot wounds in the city is self.
Confirming the 13 deaths of civilians in Wotera Rassa, which is located about 27 km from Hawassa, Shubale Buta, district head of the city of Malga, said soldiers were traveling to calm violence in a nearby town on Thursday.
"When they see people gathering near the road, they think they are there to create problems and that's how the killings happened," he told Reuters by telephone.
A Malga resident said late Friday that he saw 14 bodies after the shooting.
"My house is near the fields where people gather," he said.
"I was told by people who were there that the military was coming to town [on Thursday] and randomly fired on people who had gathered and were discussing a referendum, "he added, saying that he then went to the place where the shooting took place and counted the bodies.
Shubale said the city was "relatively calm" on Saturday.
Sidama, the largest ethnic group in the southern region, has called for a semi-autonomous country, which gave the latest political challenge to Prime Minister Abiy Ahmed.
Expectations were high that they would unilaterally declare their own territory on Thursday.
Ethiopia has been partitioned into nine semi-autonomous regions. The constitution requires the government to hold a referendum for each ethnic group that wants to form a new entity within one year of those who request it.
The Sidama Liberation Movement (SLM), which has been the main appeal for the new country, accepted the government's demands for a delay while awaiting a plebiscite before the end of the year.
The federal system in the second most populous country in Africa is designed to allow larger ethnic groups to autonomy but smaller communities such as Sidama say they have been sidelined and some have demanded their own areas.