The unidentified attackers descended on a village on the outskirts of Jos, burning about 10 houses, early on Saturday, officials said.
Some reports said the dead included the family of a Christian priest.
Clashes between rival communities – Hausa Muslims and Berom Christians – have left hundreds dead this year.
Witnesses said the men attacked the family of Rev Nuhu Dawat in the village of Mazah, 12km (7 miles) from the state capital of Jos, killing his wife, two children and a grandson.
The priest ran for his life, later telling Reuters news agency: “I leave everything to God to judge.”
Plateau State Police Commissioner Gregory Anyating told Reuters the authorities were trying to find out “the root causes of the violence”, but it had not spread to other villages.
Deadly riots in 2001, 2008 and 2010 left hundreds of people dead.
Although the clashes take place between Muslims and Christians, observers say the underlying causes are economic and political.