Gunmen attack US convoy in Nigeria, killing four.

Gunmen attacked a convoy of US Embassy staffers in southeast Nigeria, killing two local workers and two policemen. No US citizen was on the trip. The attack occurred in Anambra State, one of the epicenters of separatist violence in the region. Authorities have blamed the violence on a separatist group known as the Indigenous People of Biafra, which is leading a campaign for the region to break away from Nigeria to form an independent country. Nigerian President Muhammadu Buhari has rejected the calls for a referendum, insisting that the unity of Africa's most populous country is not negotiable.