At least seven people have been killed and dozens injured in a suicide bombing during mass at a Catholic church in northern Nigeria, officials say.
The attack happened in Kaduna, scene of many sectarian attacks.
The blast was caused by at least one vehicle being driven towards the church loaded with explosives, witnesses said. The building was badly damaged.
A spokesman for the local governor has called for calm, pleading with people on local radio not to retaliate.
The Nigerian Emergency Management Agency told the BBC that Christian youths attacked a vehicle which came to rescue survivors after the attack, smashing one of the windows.
Unconfirmed reports said at least two people were killed in reprisal attacks by Christians after the bombing.
No group has said it carried out the bombing, but Islamist group Boko Haram has been involved in several similar attacks in the area.