Some of the Chibok schoolgirls abducted by Boko Haram nearly seven years ago have finally escaped from their captors, a father of one of the girls told CNN.

Halima Ali Maiyanga, one of more than 100 young women still missing, called her father to say she and others had managed to flee Boko Haram militants Thursday.

"She asked me. Is this my daddy? Is this my daddy, and she started crying. The crying was [so] much and I couldn't hear her very well. I was crying too. I never expected to hear from her again," Ali Maiyanga said.

"The whole family is so happy. Our house is full of people who are rejoicing with us."

Ali Maiyanga said he didn't get a chance to speak to his daughter properly, as she was emotional and the call was short. But he said she and others are safe and being looked after by the Nigerian army.

He added that she was calling from a phone line belonging to a security official.

CNN has reached out to the Nigerian army for official confirmation.

It is not yet clear how many of the remaining missing girls have managed to escape.

Halima Maiyanga is the step sister of Maryam Ali Maiyanga, who was rescued by troops with a baby from a Boko Haram commander in 2016, according to Somiari Fubara, who was the therapist hired to look after the newly-freed Chibok girls in 2017.

"They are very close. She cried often about her sister," Fubara recalled of her time with them at the American University of Nigeria in Yola, Adamawa State.

In 2014, militants stormed a boarding school in the Nigerian village of Chibok and kidnapped 276 girls -- an incident which gained widespread attention and sparked an international campaign advocating for their release with the hashtag #BringBackOurGirls.

Dozens of girls escaped almost immediately after the mass abduction. Another girl was found in May 2016 when she wandered out of a Nigerian forest asking for help, according to witnesses.

Boko Haram released 21 girls to the Nigerian government after negotiations in 2016. Then 82 more girls were freed in a prisoner swap between the terrorist group and the government in the capital city of Abuja in 2017.

Since then, nothing had been heard of the 112 young women remaining in custody.