Abuja - Gunmen killed 11 people and wounded 18 others in a church in southeastern Nigeria on Sunday in an attack arising from a feud between members of the local community, officials said.
However, police believe that a man the gunmen were hunting for was not present in the church and so escaped the attack.
The attackers struck the church in Ozubulu early in the morning, said Garba Umar, head of police in Anambra state.
They were believed to have been trying to kill a local man, who was not identified by the authorities.
"The gunmen came thinking that their target was in the church but incidentally he was not," Umar said, adding that the violence may be linked to drug-trafficking.
No arrests have been made, he said.
Nigeria's southeast is predominantly Christian and the attack is a rare act of violence at a church.
Anambra State Governor Willie Obiano said the attack stemmed from a feud between members of the local community who were living outside Nigeria.
"We are not going to relent until we bring those that perpetrated this heinous crime to book," he said.
Nigeria is wracked by insecurity, with Islamist insurgency Boko Haram having killed more than 20,000 people since 2009, sparking one of the world's largest humanitarian crises.
Ethnically-charged violence is common throughout the central states and militancy is a constant threat in the oil-rich southeast.