Boko Haram militants reportedly abducted around 500 women and children at a school right after they massacred an estimated 2,000 people from Baga and neighboring town Doron Baga.

Kaltuma Wari, 40, was one of the women held hostage by the Islamist terror group who managed to escape. She divulged details of their captivity in a report in the Daily Mail and said that there are still around 500 women and children being held hostage.

Wari was brought to a girl's boarding school by Boko Haram fighters after she went out looking for her husband and children.

"They didn't touch any woman but they paid more attention to young women. They kept watch on them and they were always accompanied by gunmen wherever they went, even to the bathroom," she said.

Wari says she was forced to cook for the militants, and that many women there refused to eat out of fear for their families and loved ones.

The captivity proved too much for Wari to take and she became hysterical, but her emotional breakdown actually became her saving grace.

"They got fed up with us and (on Wednesday) around 2pm they singled us out and asked us to leave the town. We were around 100, all of us mothers. They would never allow any young woman to leave," she said.

A separate account relayed to Amnesty International said that there were around 300 women held hostage in a school in Baga. The woman who gave the testimony was released just four days after captivity, and similar account to Wari's account, said that Boko Haram fighters preferred keeping the younger women as hostages, and let go of the older women, mothers, and most of the children.

Boko Haram has killed thousands of people in northern Nigeria but shocked the world last year when it abducted 276 schoolgirls from a boarding school in the town of Chibok in April. Dozens managed to escape, but 219 still remain missing.

The remaining girls were reportedly forced to convert to Islam and were married off to Boko Haram fighters, according to the group's leader Abubakar Shekau.