The teenage bomber detonated early on Tuesday in Adamawa state as people were arriving for morning prayers.
Police spokesperson Othman Abubakar told AP that the young man detonated his explosives while mingling among the worshippers.
While there was no immediate claim of responsibility, suspicion immediately fell on Boko Haram.
The extremist group is based in neighboring Borno state and has been blamed for scores of similar attacks.