Five male officials of the U.S. consulate in Lagos and four armed mobile police officers were in the convoy when a group of unknown gunmen laid an ambush for them and opened fire in the Ogbaru local government area of Anambra on Tuesday.
The bodies of the victims were set ablaze, together with their vehicles, by the gunmen. The police suspected that some members of the outlawed Indigenous People of Biafra, which is agitating for an independent state, were responsible for the attack.
"Two other officials of the consulate are yet to be found," Echeng said, noting no American citizen was on the trip.
"Two persons of interest were arrested and they are currently assisting the police in the investigation," Echeng said.
"U.S. personnel are working urgently with their Nigerian counterparts to determine the location and status of the other members of the convoy," U.S. State Secretary Antony Blinken said, adding that the motive for the attack remains unknown as there is no evidence that it was directed against the U.S. mission.
He also stressed Washington's intention of collaborating closely with the Nigerian agents in order to bring those responsible to justice what happened.