Two Hutu women were dragged out of a minibus, lynched and their bodies set on fire by a crowd in eastern Congo.
The incident took place as inter-ethnic tensions in the region surge in the wake of massacres that have killed hundreds of civilians.
The town of Butembo where the killings took place is dominated by members of the Nande ethnic group.
The crowd in the town said the two ethnic Hutu women were travelling by minibus in North Kivu province and were militants, mayor Sikuli Uvasaka Makala told local radio.
Dozens have died in tit-for-tat killings by ethnic militia this year. Ethnic rivalries, invasions by Rwanda and Uganda and competition for land and minerals among eastern Congo's dozens of rebel groups have stoked conflict over the last two decades.
Massacres in the past two years have killed more than 700 civilians.
Migration by Hutu farmers from North Kivu through predominantly Nande areas towards Ituri province in search of more fertile land has fuelled tensions, Otto Bahizi, a Hutu tribal leader from nearby Rutshuru territory, told Reuters.
The government blames the massacres on "Ugandan Islamist rebels" but independent analysts say other armed groups are involved and ethnic rivalries likely play a role.
About 50 civilians were hacked to death this month outside Beni, some 50 km (30 miles) north of Butembo.
Hundreds of young demonstrators again took to the streets of Butembo on Wednesday to protest against the government's failure to stop the killings.
The army fired into the air and arrested about 15 people, a Reuters witness said.
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