At least 140 people were killed by gunmen who attacked remote villages over two days in north-central Nigeria’s Plateau state, survivors and officials said Tuesday in the latest of such mass killings this year blamed on the West African nation’s farmer-herder crisis.

The assailants targeted 17 communities during the “senseless and unprovoked” attacks on Saturday and Sunday, during which most houses in the areas were burned down, Plateau Gov. Caleb Mutfwang said Tuesday in a broadcast on the local Channels Television.

“As I am talking to you, in Mangu local government alone, we buried 15 people. As of this morning, in Bokkos, we are counting not less than 100 corpses. I am yet to take stock of (the deaths in) Barkin Ladi,” Gov. Mutfwan said. “It has been a very terrifying Christmas for us here in Plateau.”

Amnesty International Nigeria’s office told The Associated Press that it has so far confirmed 140 deaths in the Christian-dominated Bokkos and Barkin-Ladi local government areas of Plateau based on data compiled by its workers on the ground and from local officials, though locals feared a higher death toll with some people unaccounted for.

Some of the locals said that it took more than 12 hours before security agencies responded to their call for help, a claim the AP couldn’t independently verify, but which echoes past concerns about slow interventions in Nigeria‘s deadly security crisis, which has killed hundreds this year, including in Plateau.

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