Abubakar Zakari Adamu told The Associated Press that the figure includes a canvassing of local hospitals in Kaduna.
Adamu said others were seriously wounded by the blast.
The bomb exploded on Sunday morning as churchgoers in the city on the dividing line between Nigeria’s largely Christian south and Muslim north attended Easter services.
Both the UK and the US warned its citizens that violence was possible in Nigeria this weekend.
A radical Islamist sect known as Boko Haram has been carrying out attacks across the country.- AP