A suspected suicide attacker slammed a car bomb into a church during services on Sunday in the Nigerian city of Kaduna, killing two other people and sparking reprisal attacks by Christians.
Christian youths took to the streets with machetes and sticks afterward, targeting people they believed to be Muslims as anger again boiled over due to the repeated church bombings in recent months, an AFP correspondent reported.
A vehicle for rescue workers was attacked in the ensuing violence, but there was no indication that rescuers were wounded.
"At least three people are confirmed dead," a rescue official said on condition of anonymity because he was not authorised to give out figures. He was speaking of the toll from the suicide bombing.
He added later that the toll included the suspected attacker and that there were a number of injuries.
The strong blast that saw the attacker ram what residents said was an SUV into St. Rita church shook the neighbourhood and led to the reprisals in the city previously hit by violence blamed on Islamist extremist group Boko Haram.
The rescue source said the attacker had sought to drive into the church, but seemed to have hit a barrier. Others in the area said the bomber continued to drive after hitting the church wall and made his way inside the church premises.
"All of a sudden it drove on high speed and rammed into the church wall, forcing its way into the church premises," said witness Samuel Emmanuel.
"Initially I thought the driver had lost control of the vehicle. Suddenly there was a huge explosion as the car reached the church building. It was dust, fire and smoke all over."
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 ..."
He said later that a rescue vehicle had been attacked in the violence afterward, but no workers were wounded.
An AFP correspondent said mobs were yelling "why the church?" and some were carrying weapons, including machetes. Local elders were seeking to restore calm.
Residents had earlier spoken of clashes having broken out between Christian and Muslim residents.
The explosion occurred in the Malali area of the city. Kaduna, a major city in Nigeria's north, has been previously hit by attacks blamed on Boko Haram.
The attack came after Friday's Muslim Eid al-Adha holiday, but it was not clear if there was any link.
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.