What you need to know:
- The death toll include a suspected attacker
An attacker attempted to slam a car bomb into a church during service on Sunday, killing at least three people, including himself, while wounding others, a rescue official said on Sunday. Read (Gunmen disguised as police kill 21 at Nigeria mosque)
"At least three people are confirmed dead," the official said on condition of anonymity because he was not authorised to give out figures. He added later that the toll included the suspected attacker.
He added later that the toll included the suspected attacker and that there were a number of injuries.
The strong blast shook the neighbourhood and led to fears of a fresh outbreak of reprisal attacks and clashes between Christians and Muslims.
The source said the attacker had sought to drive into the church, but seemed to have hit a barrier. There were conflicting claims about whether he was able to eventually make it inside the church or not.
A spokesman for Nigeria's National Emergency Management Agency said it had received reports of a bomb blast in the area of a Catholic church and rushed rescuers to the scene.
"They were talking about a bomb explosion," said Yushau Shuaib of the reports, while adding that his agency was however seeking to confirm details.
"A number of casualties evacuated to hospitals. The incident was suspected to be triggered by a suicide bomber in a car ..."
Residents spoke of a loud explosion and said there had been claims of clashes breaking out afterward between Christians and Muslims.
"There was a loud explosion and I could see smoke on the horizon," one resident said. Another resident also reported hearing the blast.
The explosion was said to have occurred in the Malali area of the city. Kaduna, a major city in Nigeria's north, has been previously hit by attacks blamed on Islamist extremist group Boko Haram.
In June, Boko Haram claimed responsibility for three suicide attacks on churches in Kaduna state, where the city of Kaduna is located, which led to deadly rioting. Dozens of people were killed in the violence.
Boko Haram's insurgency in northern and central Nigeria has led to more than 2,800 deaths since 2009.
While Muslims have often been its victims, it has in recent months specifically targeted churches.
President Goodluck Jonathan has said the group is seeking to incite a religious crisis in Africa's most populous nation and largest oil producer, roughly divided between a mainly Muslim north and predominately Christian south.
Kaduna is a large city in Nigeria's north and includes a sizable Christian population.
Nigerians have grown increasingly frustrated with security forces' inability to stop Boko Haram attacks, and there have been warnings of more reprisals if the violence continued.
Some Evangelical church leaders in Nigeria have said Christians may be forced to defend themselves if something is not done to address the violence.