But some church leaders there are concerned that the authorities have not done enough to rescue the girls, who were ages 16 to 18 at the time of the kidnapping on April 14, 2014. About 50 of the girls escaped, but 219 remain missing.

The abduction shocked the world and gave rise to a global online campaign, #bringbackourgirls. U.S. first lady Michelle Obama joined the campaign, as did Malala Yousafzai, the Pakistani schoolgirl shot by the Taliban after campaigning for girls’ education.

Still, the majority of the girls have never been found.

“The whole nation has failed these children and we must repent,” said a prominent Nigerian evangelical pastor, Tunde Bakare, during a sermon to mark global action week for the abduction’s second anniversary.

Bakare urged Nigerian President Muhammadu Buhari to prioritize the girls’ rescue, saying that if the children’s parents were politicians or elite clergy, they would have been rescued, according to The Punch, an online newspaper.

Boko Haram has allegedly demanded $50 million in ransom to release the 219 girls, a development the government has denied.

Recently, church officials in Maiduguri town said they had seen the ransom demand coming.

“It’s most likely they are all intact and together since they want to use them for ransom,” the Rev. John Bakeni, the Maiduguri Roman Catholic diocesan secretary, said in a recent interview.

Meanwhile, in a new report titled “Beyond Chibok,” UNICEF says that suicide attacks involving children have increased in Cameroon, Chad and Nigeria and that girls formed 90 percent of the child attackers. Thousands of children, in addition to the Chibok schoolgirls, have disappeared in those countries, the report says.