Nigeria church gun attack
The police said that the killing was the work of a lone attacker - Representational ImagePIUS UTOMI EKPEI/AFP/Getty Images

At least 11 people died and many others left critically wounded after gunmen attacked a church in southeastern Nigeria, authorities said.

Witnesses said five gunmen stormed St Philip's church in Ozubulu, near the city of Onitsha, at 6am local time (BST), and opened fire on worshippers, Aljazeera reported.

However police said that the killing was the work of a lone attacker.

Parish priest Jude Onwuaso told BBC that a "boy or man" entered the church and started shooting.

"After the first round, there was second round and I guess it was during the second round that people were shot dead. When I came back I discovered that some of my parishioners were dead, about five or six I saw shot dead bleeding.

"A lot of people were injured, some were shot in the stomach, some were shot in the head and some were shot in the hand."

Communications director for the Nnewi Diocese, the Reverend Hygi Aghaulor said that the community was praying for the wounded.

No group has claimed responsibility for the attack, but police say a manhunt has been launched. Anambra State Police Commissioner Garba Umar said the violence could be linked to drug-trafficking.

Authorities said they do not believe that the militant Islamist group Boko Haram was behind the attack. Fighters of the armed group have attacked hundreds of churches and mosques in Nigeria's mainly-Muslim north since 2009.

They have killed at least 20,000 people and forced around 2.6 million people to flee their homes, sparking a humanitarian crisis in the country's northeast.

A recent unverified video clip showed Boko Haram militants publicly executing eight people in a village in northeast Nigeria for opposing Sharia law.

The video, seen by AFP news agency, reportedly featured a man wearing a white turban who told the villagers that those being executed were "apostates (who) have left the fold of Islam".