Security forces at a road block nearby said the bomber forced his car through the checkpoint and drove into the church in Yalwa, on the outskirts of the city of Bauchi.
A Reuters reporter at the scene counted 12 bodies being pulled from the building.
“I was just in the area when I heard a huge blast. The sound was so loud, my ears are still ringing,” said Samuel Etudu, who was outside the church when it exploded.
It was not clear who was responsible for the attack, although churches have been targeted by militant Islamist group Boko Haram this year – who are increasingly using suicide bombers.
The group have been blamed for hundreds of killings in bomb or gun attacks over the past two years.
Gunmen killed at least 15 people and wounded many more on April 29 in an attack on a university theatre being used by Christian worshippers in Kano, northern Nigeria’s main city.No tags for this post.