Gunmen killed at least 32 people and set houses on fire during a “terrible” attack in western Ethiopia.
Local authorities said the rebel Liberation Army (OLA) was to blame for the attack in the state of Oromia.
Residents said dozens of people were surrounded and killed and the cattle were stolen.
Prime Minister Abiy Ahmed suggested that the attacks could be based on identity. Ethnic violence has increased since he took office in April 2018.
OLA is an armed group accused of kidnappings and bombings in western and southern Ethiopia. OLA broke away from the Oromo Liberation Front (OLF), an opposition party that spent years in exile and returned to the country after Abiy took office in 2018.
A local official told the BBC that a team was to be sent to the Guliso district – a place of violence – to investigate, assuming that the number of victims could be “high”.
The Ethiopian Human Rights Commission (EHRC) said up to 60 “armed and unarmed assailants” were involved in the attack, which took place on Sunday.
Members of the Amhara ethnic group, the second largest ethnic group in the country, were reported to have been targeted. The Amharic branch of the ruling Prosperity party also issued a statement in support of the EHRC report.
The survivor told the AFP news agency that security forces stationed in the area on the left and OLA then rounded up civilians.
“After they gathered us, they opened fire on us and then looted cattle and burned houses,” they said.
Mr Abiy Ahmed later said that “measures have been taken against the attackers”.
“I am deeply saddened by the ongoing attacks on Ethiopians based on identity, “He wrote on Twitter.
In June, a wave of ethnic unrest erupted after the killing of popular singer Oromo Hachalu Hundessa, killing more than 150 people.