The gunmen attacked the office of a vigilante group in the community, the police said.
Suspected members of the outlawed Indigenous People of Biafra (IPOB) have killed the traditional ruler of Obudi Agwa, Ignatius Asor, in Imo State.
The incident happened around 12:30 p.m. on Monday in Agwa, a community in Oguta Local Government Area of the state.
The police spokesperson in the state, Michael Abattam, disclosed this in a statement on Monday.
He said the slain monarch had allowed the terror group inside his palace after they disguised as people in distress and who had come to report an emergency situation to the royal father.
Mr Abattam said the suspected IPOB members also killed two aides of the monarch during the attack.
"In the process of explaining the reason for their visit, they brought out guns, shot and killed the Eze and two of his aides, and hurriedly fled the palace," he said.
The hoodlums stormed the community in four vehicles and two motorcycles in company of a woman, he said.
The police spokesperson said the gunmen also attacked the office of a local vigilante group in the community and killed one person, believed to be a vigilante operative.
"The corpses have been removed and deposited in the mortuary, and the community fortified with enough police operatives," said Mr Abattam, a chief superintendent of police.
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He said police operatives "raced" to the monarch's palace in response to a distress call about the incident, but that the hoodlums had fled before they could arrive the scene.
The Commissioner of Police in Imo State, Ahmed Barde, has condemned the attack and appealed to residents to remain calm, Mr Abattam said.
Mr Barde assured the people of the community and other residents of the state, that investigation had commenced into the incident.
The police commissioner maintained that the police "will leave no stone unturned until the perpetrators are arrested" and made to face the law.
He urged the residents to assist the police with "credible information" and report criminal activities in their community to the police.
Worsening insecurity
Like other states in Nigeria's South-east, security has deteriorated in Imo with frequent attacks by armed persons.
The attacks often target security agencies, government officials and facilities.
The Nigerian government has accused the outlawed IPOB of being responsible for the deadly attacks in the region. But the group has repeatedly denied their involvement in the attacks.
IPOB is leading agitation for an independent state of Biafra which it wants carved out from the South-east and some parts of the South-south.
