Police in northwest Nigeria's Kebbi state told AFP Sunday that the death toll from an attack by a gang of cattle thieves on seven villages Thursday had risen to 88.
The region has struggled with decades-long communal clashes over resources but more recently some groups have become more violent, looting, killing and kidnapping for ransom.
"Initially 66 bodies were recovered but 22 more have been found," Kebbi state police spokesman Nafiu Abubakar said, adding that the search for more bodies was ongoing.
Dozens of assailants on motorcycles attacked seven neighbouring villages in Danko-Wasagu district on Thursday, Abubakar said.
The gunmen targeted the villages of Koro, Kimpi, Gaya, Dimi, Zutu, Rafin Gora and Iguenge, he said.
Many people were still unaccounted for Sunday after fleeing the attacks.
"The search is still going on and more bodies could be found. So, the toll is not conclusive yet," said Abubakar.
Policemen were deployed to the area over the weekend to forestall further attacks, he said.
The assailants were believed to have launched the attacks from neighbouring Zamfara or Niger states where criminals are known to maintain camps.
In April, nine policemen were killed in the area in a shootout with gunmen who invaded a village in nearby Sakaba district to steal livestock, Abubakar told AFP at the time.
Northwest and central Nigeria are a hub of criminal gangs known locally as bandits, who raid villages, harass residents and burn down homes.
The gangs maintain camps in Rugu forest which straddles Zamfara, Katsina, Kaduna and Niger states.
Nigeria's security forces, who are also battling a more than decade-long jihadist insurgency in the northeast of the country, are being stretched thin.
Gangs in the northwest have recently stepped up attacks on schools, kidnapping hundreds of students to squeeze ransoms from authorities and parents.
More than 700 children and students have already been kidnapped by gunmen for ransom since December, often from schools in remote areas, where pupils live in dormitories with little security protection.
State authorities in Niger state said they were negotiating with gunmen who seized 136 children from an Islamic seminary last weekend.
The attackers released 11 of the pupils who were "too small and couldn't walk" very far, the authorities previously said.
Nearly 700,000 people have been internally displaced in northwest and north central Nigeria in February, according to the UN's migration agency IOM, as a result of violence.
In Zamfara, Doctors without Borders (MSF) said it was struggling to respond to growing needs.
Between January and April, MSF said it treated 10,300 children in Zamfara for severe acute malnutrition, measles, malaria and other conditions.
"This is 54 percent higher than in the same period last year," said an MSF doctor, Godwin Emudanohwo.
"People here need food, safe water and vaccinations now," said Emudanohwo in a statement.
"What is happening here is a humanitarian emergency that needs urgent attention and a fast and proper response," said Froukje Pelsma, MSF head of mission in Nigeria.