Explosions hit churches in four cities in Kaduna state in the latest in a series of attacks on Sunday congregations in the majority Muslim north of the country.
There was no immediate claim of responsibility for the attacks, but Nigeria's al-Qaeda-linked Islamist terror group Boko Haram has carried out at least 10 similar strikes so far this year.
Authorities in Kaduna imposed a 24-hour curfew ordering everyone to stay indoors after gangs of young men blocked a major highway heading south out of the state capital and dragged Muslims from their cars.
There were unconfirmed reports that several were killed, and that the attacks were to revenge the bombings earlier in the day.
Four children playing outside a church in Zaria were among the first victims of yesterday's blasts, at the Evangelical GoodNews Church in the city's Sabon-Gari district. Read more