Islamist extremist group Boko Haram has taken responsibility for last week’s kidnapping of hundreds of schoolboys from a school in north-western Nigeria.

Gunmen descended upon the Government Science Secondary School in Kankara on Friday, Dec. 11, and carried out a mass kidnapping. About 330 of the school’s 800 students remain missing, although some were able to escape.

One 17-year-old boy told BBC Hausa he crawled through the forest for miles to escape the abductors.

The Daily Nigerian said it received an audio message from Boko Haram leader Abubakar Shekau, claiming the group was behind the kidnapping.

Shekau said the group abducted the boys because Western education conflicts with the tenants of Islam. Authorities originally thought bandits sometimes associated with Boko Haram were responsible for the attack.

Boko Haram has carried out several school kidnappings over the past 10 years, although most of the abductions took place in the north-east. The recent attack has sparked fears of a growing wave of violence in the area.

On Friday, many boys were able to escape as gunfire was exchanged between the attackers and police.

Students told local news agencies that some pupils were able to flee after abductors ordered the boys to walk through the forest.

The government and the kidnappers are currently negotiating the fate of the boys, said Garba Shehu, a spokesman for Nigerian President Muhammadu Buhari.

“The kidnappers had made contact and discussions were already on, pertaining to the safety and return” of the children to their homes,” Shehu said on Twitter.

Authorities also said they had located the boys’ position. A rescue operation was launched on Saturday after their position was located.

Boko Haram’s most serious mass abduction took place in 2014, when the group abducted 270 schoolgirls from the Government Secondary School in Chibok. About 100 of the girls are still missing.

Since the group waged an insurgency in 2009, tens of-thousands of people have lost their lives, and millions have been forced out of their homes.

Friday’s kidnaping heightened parents’ fears about the safety of their children in local schools, which had been starting to reopen amid the pandemic.

President Muhammadu Buhari has been criticized for not showing empathy to the victims of the abduction, and has been accused of mishandling security operations against the attackers.

“It’s absolute incompetence and an uncaring, indifferent ruling class that does not understand what it means to govern,” former Nigerian Education Minister Oby Ezekwesili told the BBC.

“Here we are as a country just completely showing ourselves as completely unserious when it comes to the matter of human life, especially that of our children.”