At least 12 people were killed and several others injured or kidnapped in a spate of attacks in northeast and central Nigeria, police and officials said Monday.

Insecurity is a major concern in Africa’s most populous country as a new president is set to be sworn in next month following an election disputed by the opposition.

In northeastern Adamawa State on Monday, unidentified gunmen stormed Dabna village in Hong district, resulting in the “unfortunate murder of three (persons),” local police spokesman Suleiman Nguroje said, adding that homes were set ablaze.

No group has claimed responsibility, although Boko Haram jihadists are known to launch occasional attacks in the area from their Sambisa forest enclave in neighboring Borno State.

Also on Monday, gunmen attacked communities in Oganenigu, in the Dekina district of central Kogi State, according to local authorities.

The governor’s spokesman Muhammed Onogwu said that a local politician was killed while others were “affected by this ugly and unfortunate attack.”

On Sunday, gunmen stormed a church in Akenawe-Tswarev village in central Benue State, killing a worshipper and kidnapping three others, according to Salome Tor, political administrator of Logo district in which the village is located.

“The attackers burst into the church during morning worship and shot dead one person and kidnapped three others, including the priest,” Tor said.

Two other worshippers were seriously injured and taken to hospital for medical treatment, she said.

Tor did not say who was responsible for the attack, but Benue has for years been a hotbed of deadly communal unrest between herders and farmers.

In central Niger State on Saturday, gunmen suspected to be from criminal gangs attacked several villages in Mashegu and Munya districts, killing at least seven people and abducting 26 others, according to a local official.

Umar Jibrin Igede, Mashegu district political administrator, said the attacks were the latest in a series of raids on villages in the area in the past two weeks and that many residents had fled their homes.

Police in Niger State did not respond to AFP‘s request for comment on the attacks and kidnappings.

President Muhammadu Buhari, who is stepping down in May, has left his successor Bola Tinubu a country facing a jihadist insurgency in the northeast, violent criminal gangs in the northwest and center, and secessionist agitation in the southeast.