Gunmen attacked a US convoy in southeast Nigeria’s Anambra State on Tuesday, police and a US official said, killing four people and abducting three others. “No US citizen was in the convoy,” said police spokesman Ikenga Tochukwu. The gunmen “murdered two of the Police Mobile Force operatives and two staff of the consulate,” he said, before setting their vehicle “ablaze”. The attack took place on Tuesday at “3:30pm (14:30 GMT) along Atani, Osamale road” in Ogbaru district, according to the police. Joint security forces deployed to the scene, said Tochukwu, 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 spokesman 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.” Separatists operate in the region where they have escalated their attacks in recent years, usually targeting police or government buildings. Nigerian officials blame the 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. Separatism is a sensitive issue in Nigeria, where a declaration of an independent Biafra Republic by Igbo army officers in the southeast in 1967 triggered a three-year civil war that left more than one million dead. IPOB’s leader Nnamdi Kanu is in government custody and faces trial for treason after being detained overseas and brought back to Nigeria.