The latest attack is not directly linked to the ongoing separatist conflict in Tigray, although analysts suggest the concentration of soldiers and security forces in the north around Tigray has created a security vacuum in the rest of the country.
At least 102 people died in the Wednesday morning attack. The Ethiopian Human Rights Commission (EHRC) has published images from the scene of the massacre, taken by survivors, describing the pictures as "worrying evidence".
In #Ethiopia's Benishangul-Gumuz, an armed group shot at residents, set fire to homes as they lay asleep, killing at least 100 people.
— Ethiopian Human Rights Commission (@EthioHRC) December 24, 2020
The attacks followed the departure of federal troops positioned to restore calm - a sign of a severe decline of human rights protections there. pic.twitter.com/TglREUuK0z
Belay Wajera, a farmer in the western town of Bulen, told the Reuters news agency that he counted 82 bodies in a field near his home after the dawn attack on Wednesday.
He and his family awoke to the sound of gunshots, he said. Wajera's wife and five of his children were shot dead; he was shot in the back. Four other children who escaped are now missing.
Another resident of the town, Hassen Yimama, said armed men stormed the area at dawn. He told Reuters that he had counted 20 bodies in an area separate from that described by Belay Wajera. The assailants shot Yimama in the stomach.
A local doctor said he and colleagues had treated 38 injured people, most suffering from gunshot wounds. Patients had told him of relatives killed with knives, and of gunmen who set houses on fire and shot at people trying to escape, he said.
Other survivors told officials of the EHRC that the attackers had destroyed crops. One witness counted 18 fires in the fields. Some of the survivors claim to have recognised the attackers.
The attack came just one day after the Ethiopian Prime Minister, Abiy Ahmed, and the army chief of staff, Birhanu Jula, visited the region to urge calm after a number of clashes between rival ethnic groups in recent months. The most recent incident in the area was on 14 November, when 34 passengers in a bus lost their lives.
Security was briefly strengthened in the area earlier this week, in preparation for the visit by the government and army leaders, but survivors of Wednesday's attack say no police or soldiers were on duty when the assault was launched. Federal forces have been concentrated in the north of Ethiopia since fighting broke out in Tigray in November.
The western region of Benishangul-Gumuz is shared between people of the shinasha, oromo and amhara ethnic groups, according to the EHRC. Prime Minister Ahmed has blamed instability in western Ethiopia on Sudan, asking Khartoum to strengthen border security against the transit of fighters who, Abiy claims, are trained and armed on Sudanese territory.
There has been no official statement from the prime minister's office on the latest attack.
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