Nigerian officials say 21 of the "Chibok girls" kidnapped by militant group Boko Haram in 2014 have been released.
A spokesman for Nigerian President Muhammadu Buhari said on Twitter Thursday that the 21 girls are in the custody of the Department of State Services, Nigeria's main intelligence agency.
The spokesman, Mallam Garba Shehu, said the girls' release was the result of talks between Buhari's administration and Boko Haram that were brokered by the International Red Cross and the Swiss government.
He said "negotiations will continue" for the other kidnapped girls, adding that the girls released will be handed over to Vice President Yemi Osinbajo, and that their names will soon be made public.
The Associated Press, citing a Nigerian military officer, reports that the girls were swapped for four detained Boko Haram leaders.
Released in Banki, flown to Maiduguri
Sources in Nigeria say the 21 girls were released late Wednesday in the northeastern town of Banki and were flown by helicopter to the Borno state capital, Maiduguri.
President Buhari, who is traveling to Germany, said on his Twitter account that he was briefed on the girls release before leaving for Germany on official business. "I welcome the release of 21 of our Chibok Girls, following successful negotiations," he said.
FILE - Martha Mark, mother of kidnapped schoolgirl Monica Mark, cries as she displays her photo in the family's house in Chibok, Nigeria, May 19, 2014
2 years in captivity
Boko Haram kidnapped nearly 300 girls from a secondary school in the Borno state town of Chibok in April 2014. Dozens escaped, but 219 remained captive.
Buhari has repeatedly vowed to rescue the girls and crush Boko Haram, which has frequently attacked schools as part of its seven-year insurgency in northeastern Nigeria. The group's name is roughly translated as "Western education is forbidden."
These are the first of the Chibok girls to be rescued as a result of government action. One of the girls was found, pregnant, in a forest in May.