A string of bombs targeted churches in five Nigerian cities, leaving dozens of people dead and wounded.
An aide worker says a police station and a state security building were also bombed.
A witness says locals are blaming the attacks on a militant Islamic sect called Boko Haram.
Nigeria's president, Goodluck Jonathan, condemned the attacks, saying all peace-loving Nigerians must rebuke them.
Today's blasts stirs memories of attacks on five churches in Nigeria on Christmas Eve last year. Dozens of people died in those attacks in the city of Jos.