Boko Haram, which is led by Abubakar Shekau, shown in a May 2014 file photo, is accused of kidnapping and abusing children.(AP Photo)

NAIROBI -- After years in a Boko Haram camp, the children had forgotten their native language. They couldn’t even remember their names.

They just stared past Christopher Fomunyoh when he tried to engage them. It was a rare glimpse at the human toll left by the extremists who have been fighting to create an Islamic state in Nigeria and surrounding areas.

Fomunyoh, regional director at the Washington-based National Democratic Institute, visited the children recently at an orphanage in the city of Maroua in northern Cameroon. They had been rescued by the country's military in November from a squalid Boko Haram encampment near the border with Nigeria.

This is what he saw:

One hundred children, aged 5 to 17, without shoes in an orphanage built for 20. Hard benches for sleeping. A shortage of rice. Boys who appeared to be speaking broken Arabic, rather than one of the many languages native to Cameroon.

“There was a blankness in their eyes,” he said.

[Read: Boko Haram may have killed 2,000 people]

Christopher Fomunyoh (Washington Post) Christopher Fomunyoh (Washington Post)

Boko Haram is now under siege by Nigerian and other African troops. If the insurgents are pushed back, hundreds more children like these could soon be found. But what condition will they be in?

Fomunyoh and others working with the newly rescued children were left to unravel the mystery of what happened to them. Were they fighters or merely students? How long had they been captive? How had they forgotten their names? Where were their parents?

[Read: South African mercenaries join fight against Boko Haram]

No one knew. Last week, the small number of employees at the Institution Camerounaise de L'enfance was focusing on teaching them how to count to 10 in French.

“Right now, there’s not full comprehension of the damage of this crisis,” said Fomunyoh, who is now trying to provide assistance to the children. “Even if kinetic operations were to end soon and Boko Haram was taken off the battlefield, it would take years to really address consequences in humanitarian terms.”

In April 2014, Boko Haram grabbed the world’s attention when fighters abducted 200 schoolgirls in northern Nigeria. But it wasn’t the first time the group conducted a mass kidnapping.

The rate and scale of the group's abductions have increased steadily since 2013, according to a report from the U.S.-based Watchlist on Children and Armed Conflict. Many of the victims have been raped, and only a few have escaped, activists say.

The group “forcibly converts the Christian women and girls they capture to Islam and often coerces them and other female abductees into marriage,” said Watchlist’s 2014 report.

According to Human Rights Watch, Boko Haram has allegedly recruited boys as young as 12 years old to fight for the group.

Still, Fomunyoh wasn’t prepared for what he saw. And he worried about what would come next for the children.

"Without substantive work to reeducate them and help them survive in a normal society, these are potential troublemakers,” he said.

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