The attackers "murdered two police operatives and two staff of the US consulate and set their bodies and their vehicles ablaze."
Gunmen on Tuesday attacked a United States convoy in Anambra State, south-east Nigeria, killing four people, CNN reports.
Persons killed include two personnel from the US consulate and two police officers, while three others were kidnapped, local police and US officials said.
The attackers "murdered two police operatives and two staff of the US consulate and set their bodies and their vehicles ablaze," CNN quoted Anambra police command as saying.
The personnel who were killed were not US citizens, according to the White House and the local police.
"No US citizens were involved and therefore there were no US citizens hurt," CNN quoted John Kirby of the US National Security Council as saying. "We are aware of some casualties, perhaps even some killed."
According to CNN, Ikenga Tochukwu, a deputy superintendent of police, said that when the assailants saw security forces, they made away with two police operatives and a driver of the second vehicle in the convoy, reiterating that no US citizen was in the convoy.
Police said that joint security forces "have embarked on a rescue and recovery operation in the area."
A State Department spokesperson said Tuesday that "Mission Nigeria personnel are working with Nigerian security services to investigate."
"The security of our personnel is always paramount, and we take extensive precautions when organising trips to the field."
Although no group has claimed responsibility for the attack, Anambra is one of the south-east states that has suffered attacks from gunmen believed to me members of the outlawed separatist group, IPOB.
Hundreds of people have been killed and many others kidnapped in Anambra and neighbouring states like Enugu and Imo.
The group seeks an independent country of Biafra for Igbos from South-east Nigeria but does not enjoy the support of majority of Igbos.
IPOB leader Nnamdi Kanu is currently being detained by the federal government in Abuja where is facing treason charges.
