by Ajadi Daniel
Sources said the girls were swapped for four Boko Haram militants in northeast Nigeria.
There are reports that negotiations are ongoing to ensure release of the other girls.
The Presidency said in a statement that the four militants were brought in a military helicopter to Banki from Maiduguri. They were then driven to Kumshe in ICRC vehicles.
The Chibok girls were taken from Kumshe by helicopter to Maiduguri, the capital of Borno state.