MAIDUGURI, Nigeria (AP) - More than two years after their abduction, 21 of the missing Chibok schoolgirls have been released by Boko Haram in northeast Nigeria, a government spokesman said today.

“The release of the girls, in a limited number is the outcome of negotiations between the administration and the Boko Haram brokered by the International Red Cross and the Swiss government,” presidential spokesman Garba Shehu said in a statement. “The names of the released girls follows shortly.”

The successful negotiations mark the first major breakthrough since the Islamic militant group kidnapped 276 girls from a school in the small town of Chibok in Borno state April 14, 2014. Some of the girls have managed to escape but, even with today’s release of 21, the fate of nearly 200 others remains unknown.

Some are believed to have been killed in the Nigerian military’s airstrikes on Boko Haram.

Shehu said the negotiations with Boko Haram will continue to secure the release of the remaining girls. Nigerian President Muhammadu Buhari welcomed the girls' release but he “cautioned Nigerians to be mindful of the fact that more than 30,000 fellow citizens were killed by terrorism,” Shehu said in a statement.

Pogu Bitrus, a village elder in the Chibok community, confirmed to ABC News that the town received word of the girls’ release today and is awaiting their arrival.

In May, Nigerian troops and a vigilante group found one of the missing Chibok schoolgirls in the vast Sambisa Forest, which covers over 23,000 square miles in northeast Nigeria and is a stronghold of Boko Haram.

The teenager was identified by the army as Amina Ali. She was found with a 4-month-old baby, who authorities said is her daughter, and a man identified by the army as Mohammed Hayatu, who said he is her husband.

Hayutu was detained for questioning as a suspected Boko Haram militant. The three were examined by military medics and deemed stable. Amina was reunited with her mother, the army said.

Residents said the Chibok teen told her family that six of her classmates had died.

The Nigerian military’s failure to act on the girls’ kidnapping led in part to President Goodluck Jonathan’s electoral defeat to Buhari in March of last year. Since taking office, Buhari has made the war against Boko Haram a top priority, but families of the missing schoolgirls have grown frustrated as months have passed without their rescue.

Buhari has said corruption from previous administrations was largely to blame for the army’s inability to quickly defeat Boko Haram, which aims to overthrow the federal government and establish an Islamic state in West Africa.

In the past year, Buhari has replaced the military top brass and relocated the command center to Maiduguri in Borno state, the heartland of Boko Haram’s seven-year insurgency that encompasses the town of Chibok.