The shooting happened in the city of Potiskum at about 2:00 a.m. on Tuesday, Xinhua reported.
"They opened fire on the worshipers while praying and observing the Christmas celebration at about 2 a.m. local time on Tuesday, " a security official said.
"Five of the worshipers died and some were injured. The gunmen also burnt down the church after the killing," Barnabas Musa, a Potiskum resident who also lost a relative in the attack.
The pastor of the church was among those killed, Musa said.
No arrests have been made; police are investigating the incident.