Gunmen attacked a US convoy in southeast Nigeria's Anambra State on Tuesday, killing four people and abducting three others, police and a US official confirmed.

"No US citizen was in the convoy," said police spokesperson Ikenga Tochukwu.

The gunmen "murdered two of the Police Mobile Force operatives and two staff of the consulate," the spokesperson pointed out, before setting their vehicle "ablaze".

According to the police, the attack took place on Tuesday at "3:30 pm (14:30 GMT) along Atani, Osamale road" in Ogbaru district.

Joint security forces deployed to the scene, Tochukwu said, but the gunmen managed to abduct two police operatives and a driver.

A "rescue/recovery operation" was underway Tuesday evening, he added in his statement.

US National Security Council Spokesperson John Kirby confirmed the attack during a briefing with reporters in Washington DC.

"A US convoy of vehicles was attacked. What I can tell you is that no US citizens were involved," Kirby said.

The State Department also confirmed the attack.

"U.S. Mission Nigeria personnel are working with Nigerian security services to investigate," a spokesperson said.

"The security of our personnel is always paramount, and we take extensive precautions when organizing trips to the field."

Nigerian officials blame such attacks on the Indigenous People of Biafra movement (IPOB), who they describe as a terrorist group, along with its armed wing, the Eastern Security Network.

IPOB has repeatedly denied responsibility for the violence.

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