Attackers killed 88 people in Nigeria's Kebbi state on Thursday, spurring its governor to pledge a bigger deployment of security forces on Sunday as insecurity spreads largely unchecked through the country's northwest.

Perpetrators swept through eight villages, killing people and sending residents fleeing, police said, giving a death toll of 88. Details began to emerge on Saturday.

A spokesperson for Kebbi Governor Abubakar Bagudu said on Sunday the attackers had come from neighbouring Niger and Zamfara states, rustling cattle and destroying crops.

Gunmen have ramped up attacks on the region's communities in recent years, forcing thousands to flee across Nigeria's northern border to Niger. The attackers have become globally notorious because of mass kidnappings at schools, with more than 800 students abducted since December.

The rampant violence has spawned a humanitarian crisis, international aid group Medecins Sans Frontieres said on Thursday.

On Sunday, the governor promised financial aid, and "requested communities in the area to be tolerant, accommodating, friendly and peaceful," his spokesperson said in a statement.