At least 1,400 students have been kidnapped from Nigerian schools since 2014, when Boko Haram militants kidnapped hundreds of schoolgirls from Borno state’s Chibok village in 2014. In recent years, abductions have been concentrated in the country’s northwestern and central regions, where dozens of armed groups often target villagers and travelers for ransom.

Kaduna state Gov. Uba Sani did not give details of the release of the 287 students abducted from their school in the remote town of Kuriga on March 7, at least 100 of them aged 12 or younger. In a statement, he thanked Nigerian President Bola Tinubu “particularly ensuring that the abducted school children are released unharmed.”

Tinubu had vowed to rescue the children “without paying a dime” as ransom. But ransoms are commonly paid for kidnappings, often arranged by families, and it is rare for officials in Nigeria to admit to the payments.

earNo group has claimed responsibility for the Kaduna kidnapping, which locals have blamed on bandit groups known for mass killings and kidnappings for ransom in the conflict-battered northern region, most of them former herders in conflict with settled communities.

At least two people with extensive knowledge of the security crisis in Nigeria’s northwest told The Associated Press that the identity of the abductors is known.

Murtala Ahmed Rufa’i, a professor of peace and conflict studies at Usmanu Danfodiyo University, and Sheikh Ahmad Gumi, a cleric who has negotiated with the bandits, said they are hiding in the region’s vast and ungoverned forests.

Arrests are rare in Nigeria’s mass kidnappings, as victims are usually released only after desperate families pay ransoms or through deals with government and security officials.