At least seven people have been killed and dozens injured in a suicide bombing on Sunday during Mass at a Catholic church in northern Nigeria, officials say.

An explosive-laden vehicle drove into St Rita's Catholic Church which was packed with worshippers when the suicide bomber struck in the Malali area of Kaduna, Nigeria, and detonated its load, ripping a hole in the wall and roof.

The BBC's Will Ross in Kaduna says many people have come to the city in recent months in search of sanctuary from violence in other parts of northern Nigeria.

Kaduna has been targeted by Islamist militant group Boko Haram in the recent past. Boko Haram says it is fighting to create an Islamic state in Nigeria, whose 160 million people are split roughly evenly between Christians and Muslims.

President Goodluck Jonathan promised to "redouble" his government's efforts to tackle terrorism and violence.

He called the attack part of an "unfortunate and unacceptable trend that threatens the peace and stability of our nation".

A spokesman for the local governor has called for calm, pleading with people on local radio not to retaliate.

The Nigerian Emergency Management Agency (NEMA) told the BBC that Christian youths attacked a vehicle that had come to rescue survivors after the attack, smashing one of the windows.

Shortly after the explosion, Christian youths took to the streets armed with sticks and knives. A Reuter's journalist reported seeing two bodies on the roadside lying in pools of blood.

"We killed them and we'll do more," shouted a youth, before police chased him and his cohorts away. Police set up roadblocks and patrols across town.

A spokesman for St Gerard's Catholic hospital, Sunday John, said the hospital was treating 14 wounded. Garkura hospital was treating 84 victims, the NEMA official said.

Many residents rushed indoors, fearing a wave of the sectarian killing that has periodically hit Kaduna. A bomb attack in a church in Kaduna state in June triggered a week of tit-for-tat violence during which at least 90 people were killed.

Boko Haram has said it carried out previous attacks on churches in Kaduna state in June. At least 50 people were killed in the bombings and the reprisals that followed.