More than 300 schoolgirls kidnapped by gunmen in increasingly lawless northwest Nigeria last Friday are still not accounted for.

Iran Press/Africa: A few days ago, gunmen attacked a secondary school in Jangebe, Nigeria, and took 317 girls as hostages. Parents are anxiously waiting for the return of their daughters and keep coming to school to ask if the school authorities have any news. 

Police in Zamfara state said they had begun search-and-rescue operations with the army to find the "armed bandits" who took the 317 girls from the Government Girls Science Secondary School in the town of Jangebe.

"There's information that they were moved to a neighboring forest, and we are tracing and exercising caution and care," Zamfara police commissioner Abutu Yaro had told a news conference.

He did not say whether those possibly moved to the forest included all of them.

School kidnappings were first carried out by jihadist groups Boko Haram and Islamic State West Africa Province but the tactic has now been adopted by other militants in the northwest whose agenda is unclear.

They have become endemic around the increasingly lawless north, to the anguish of families and frustration of Nigeria's government and armed forces. Friday attack was the third such incident since December.

The rise in abductions is fuelled in part by sizeable government payoffs in exchange for child hostages, catalyzing a broader breakdown of security in the north, officials have said, speaking on condition of anonymity.