Nigerian police have launched a search-and-rescue operation for 317 girls who were kidnapped on Friday from a school in the northwestern state of Zamfara.
It was the country's third school kidnapping in less than three months.
The latest events have revived traumatic memories of the 2014 Chibok girls' abduction by the the so-called militant group Boko Haram.
The most recent abductions are suspected to have been carried out by criminal gangs, often for ransom, and are common in the north of the country.
However, no group has claimed responsibility for the Zamfara attack.
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On Saturday, 38 people, including 24 school children, who had been kidnapped from a boarding school in Niger state in mid-February, were freed.
"They are all safe and sound but one of them is hospitalized due to extreme exhaustion, some have mild injuries or are still traumatized," a local government spokesman, Sani Idris, said.
Parents of the kidnapped girls have been left wondering if they would see their children again/Kola Sulaimon/AFP
Meanwhile, the Government Girls Science Secondary School in Jangebe, the site of the latest attack, was completely deserted following the mass abduction.
Empty metal bunk beds and abandoned clothing remained inside a building visited by AFP news agency's journalists, as parents were left wondering if they would see their children again.
The regions involved account for the greatest number of unschooled children in the world, according to the International Crisis Group. /Kola Sulaimon/AFP
There has been an increase in attacks in northwest and central Nigeria, where heavily armed criminal gangs raid villages, steal livestock, as well as kill and abduct residents after looting and torching homes.
And they have increasingly started abducting students from boarding schools.
The number of such gangs is not known, but they are attracting an increasing number of young men in regions where more than 80 percent of the population lives in extreme poverty.
The so-called bandits hide in camps in Rugu forest, which straddles Zamfara, Katsina, Kaduna and Niger states.
Despite the deployment of troops in Zamfara and Katsina states deadly attacks persist.
Shamsiya Muktar, a student of Government Girls Secondary School, escaped from her school and did not get taken away in the kidnapping on Friday. /Kola Sulaimon/AFP
"Local citizens have lost trust in the police, people are not willing to share information with the Nigerian police or other forms of security because of fear of backlash or being implicated in all kinds of things that are happening," Rotimi Olawale, founder of Youth Hub Africa, told CGTN Europe.
Nigeria's President Muhammadu Buhari has been criticized for failing to deal with the unrest, but he insisted that he "will not succumb to blackmail by bandits."
He has condemned the latest mass kidnapping as "inhumane and totally unacceptable."
"No one knows the condition of the girls. The government said they are making efforts to rescue the girls but their efforts are not good enough until our girls are safely back," a Jangebe resident Bello Gidan-Ruwa said.
The abductions have contributed to the increase in the number of children who cannot attend school, especially girls.
The regions involved account for the greatest number of unschooled children in the world, according to the International Crisis Group.
Video Editor: Terry Wilson