Police in Nigeria are investigating a second explosion after an earlier blast killed at least 16 people in the northern town of Kaduna.
Some reports suggest the number of dead is much higher but there has been no official verification.
The first bomb exploded on Sunday morning after security forces stopped a vehicle approaching a church according to witnesses.
No group has yet said it was behind the attack but the fact that a church seems to have been the target has led to speculation that the islamist group Boko Haram was responsible.
The second explosion happened in the south eastern town of Jos. A military spokesman said it was a small blast and no one was hurt.
Boko Haram carried out a number of deadly attacks in Nigeria over the Christmas holidays.