Up to 18 different admirers were injured in the early morning episode at the congregation in Ozubulu close to the city of Onitsha.
There were clashing reports about whether the assault was completed by a solitary shooter or a gathering of assailants.
Police said the shooting was the consequence of a fight between Nigerians from Ozubulu who were living abroad.
Anambra State Police Commissioner Garba Umar said the viciousness could be connected to sedate trafficking.
He said the shooter had been employed to murder a nearby man who was accepted to be in St Philip’s Catholic Church.
One of the Nigerian exiles engaged with the fight had constructed the congregation, Mr Umar included an announcement.
A nearby rights lobbyist said there was more than one aggressor and they had been focusing on the child of a neighborhood boss.
They had not discovered him at his home and ended up plainly irate when they couldn’t discover him in the congregation either, Emeka Umeagbalasi told AFP.
Witness Chukwuma Emeka said he had quite recently ventured out of the congregation to extend his legs “when I heard discharges and shouting and individuals running inside”.
“At the point when the mayhem died down I went inside, I saw my kindred church individuals dead in their very own pool blood and numerous others were shouting in torment.”
The specialists have said they don’t accept there was any inclusion by the activist Islamist aggregate Boko Haram, which has consumed many places of worship amid its uprising in the north-east of the nation.