A local resident, Bernard Matur, said the gunmen attacked Maikatako village, in Plateau state, on Monday evening, killing at least 12 people.
Matur said the unprovoked attack was to take over their land, which herdsmen have done in neighboring villages.
Meanwhile, Governor Simon Bako Lalong stated a lower fatality figure of 11 people. He added that the rising incidence of attacks and destruction of farm crops, livestock and other properties within the state was becoming worrisome and needed to be checked.
Violence between farmers and pastoralists has become increasingly common in recent years as population growth leads to an expansion of the area dedicated to farming, leaving less land available for open grazing by nomads' herds of cattle.
In October, clashes between herdsmen and farmers in the Nigerian state of Benue left at least 23 people dead.