Clashes this week between different ethnic groups in Ethiopia's Oromia region have killed at least 61 people, according to local officials.
The Ethiopian government said on Monday it was investigating the violent incidents in Hawi Gudina and Daro Lebu districts, the latest round of violence in a region hit by deadly unrest in 2015 and 2016.
Addisu Arega Kitessa, regional spokesman, said in a statement on Sunday that 29 ethnic Oromos were killed between December 14 and 17 by ethnic Somali attackers in Hawi Gudina.
The violence prompted revenge attacks in Daro Lebu, which resulted in the killing of 32 ethnic Somalis, he added.
"The region is working to bring the perpetrators to justice," Addisu wrote on Facebook.
It was not immediately clear what caused the latest violence.
It came after 16 ethnic Oromos were killed on Tuesday by soldiers trying to disperse a protesting crowd in Oromia's Chelenko town, Reuters news agency reported.
In a statement, Prime Minister Hailemariam Desalegn denounced the latest clashes and expressed his "deepest condolences to families of victims", the state-run FANA news agency said on Monday.
He also announced that a task force has been set up to investigate the attack, as well as the incident in Chelenko.
Oromia was rocked by violence in 2015 and 2016, sparked by plans to allocate farmland in the region, which surrounds the capital, Addis Ababa, for development.
Authorities later scrapped the land scheme, but anti-government protests that began in Oromia and spread into Amhara region and elsewhere flared again over political and human rights, as well as the continued detention of opposition demonstrators.
The violence, which left hundreds dead, prompted the government to impose a state of emergency in October 2016.
The measure, which was lifted in August, restricted a number of rights and led to the arrest of more than 21,000 people.