[HIGHLIGHTS] Armed attack on US convoy in Nigeria killed

The attack took place on Tuesday "at 15:30 (14:30 GMT)" in Ogbaru province, police said. The convoy did not include any U.S.

citizen, a police spokesman said. Separatists are active in the area, who have stepped up attacks in recent years. Nigerian officials attribute the attacks to the Biafra Indigenous Peoples' Independence Movement (MINU), with its military wing, the Eastern Security Network. The US State Department is involved in the investigation of Nigerian security services.