Eighty-six people have been killed in an attack by herdsmen on six villages in central Nigeria, local media reported.
Another six people were wounded and 50 homes were destroyed in the attacks in the Gashish district of Plateau state, Channels Television reported citing local police on Monday.
President Muhammadu Buhari had been briefed on the "deeply unfortunate killings," according to a post on his Twitter page.
"The grievous loss of lives and property arising from the killings in Plateau today is painful and regrettable," a second post said.
"My deepest condolences to the affected communities. We will not rest until all murderers and criminal elements and their sponsors are incapacitated and brought to justice."
State Governor Simon Lalong said a curfew had been put in place from 6pm to 6am local time (17:00 GMT to 05:00 GMT). He visited the villages involved and called for calm as the government investigated the attack.
Tensions between the state's primarily Christian farming community and the mainly Muslim herdsmen have often spilled over into violence in recent years.
Drought in the country's north has also driven the nomads and their cow herds further south in search of fresh grazing, further escalating conflicts.