Northwestern and central Nigeria have long seen clashes between farmers and herders over water and land.
Gunmen attacked villages in the Plateau state in north-central Nigeria, authorities said on Tuesday.
Northwestern and central Nigeria have long seen clashes between farmers and herders over water and land. The security crisis has led to thousands of deaths.
No group typically takes responsibility for such attacks and arrests are rare.
Nigeria's security crisis is set to be a pressing issue for president-elect Bola Tinubu, who will assume office later this month.
What do we know about the attacks?
Nigerian authorities said that 29 people were killed in the attacks and houses were set on fire.
The Associated Press (AP) news agency cited residents as saying that many villagers remained unaccounted for Tuesday evening.
The attackers targeted three villages in the Mangu area of Plateau state late on Monday.
Plateau Governor Simon Lalong said he was disturbed by the attack and directed security forces to search for the suspects.
"He (the governor) describes this as yet another attempt by crises merchants and criminals to return the state to the dark days of pain and agony," said Lalong's spokesman, Makut Macham.
Lalong directed the emergency response agency to visit the affected communities to assist victims and their families.
The Mangu area has imposed a 24-hour curfew "to ensure that the crisis does not escalate to other areas," police spokesman Alfred Alabo said.