At least 80 people were killed during ethnic clashes in the volatile nation of South Sudan, an official said on Monday.

At least 50 others were wounded when heavily armed men from the Murle ethnic group attacked six villages in Uror county in Jonglei state on Saturday, county commissioner John Dak Gatluak said.

The death toll was likely to rise, as the search continued for missing villagers who had fled into the bush to escape the attackers who were armed with rocket launchers and machine guns, the commissioner said.

Local authorities believe Saturday’s attack was in revenge for a similar incident in February, when men from the Lou Nuer ethnic group had raided cattle and abducted children from the Murle.

Cattle raiding has occurred for centuries between ethnic groups in the East African nation, and children are sometimes abducted during raids to be used as domestic slaves.