Nigeria church bombed in Bauchi, Boko Haram flashpoint
Witnesses at the scene in the city of Bauchi said they heard a blast near St John's Church, possibly in a car park.
Bauchi has often been targeted by the Islamist Boko Haram group, which wants to impose Sharia law across Nigeria.
Sunday attacks on churches took place regularly earlier this year but had eased in recent months.
Attacks in central and northern Nigeria blamed on Boko Haram have killed some 1,400 people since 2010.
On 16 September, Nigerian security forces said they killed Boko Haram's spokesman Abu Qaqa in a gun battle in the northern state of Kano.
However, the group has not confirmed his death.
Meanwhile, the military in Yobe state imposed a 24-hour curfew on two cities as soldiers went door-to-door, searching for Boko Haram members.
"Residents of the two cities are to remain indoors until further notice to enable security personnel to fish out Boko Haram terrorists," a military spokesman told the AFP news agency.