Lagos: Thirty Nigerian students abducted in the northwest by gunmen have been released, Kebbi state governor's office announced Thursday, but dozens remain in captivity in the state.

The students of the Federal Government College arrived in the Kebbi state capital on Thursday and “shall undergo medical screening and support while being reunited with their families,” according to Yahaya Sarki, Kebbi state governor's spokesperson.

A statement issued by Sarki did not give details of how the students were freed but added that efforts are ongoing to secure the release of those still in detention. Kidnap ransoms for the release of hundreds of abducted students in the West African country are common.

The Kebbi students were abducted on June 17 when the gunmen stormed their school in Birnin-Yauri, which is about 220 kilometers (136 miles) from the state capital. The assailants overpowered security officers guarding the school and killed a police officer before driving off with the students.

Authorities could not provide the exact number of those missing from the Kebbi school after the attack but residents had said they were more than 70.

In the weeks following the incident, six of the students were rescued while one was killed. Security forces continued to hunt for their abductors believed to be bandits operating out of abandoned forests in northwest and central parts of Nigeria.

The Kebbi school abduction is just one out of at least 10 cases of school abductions this year in the West African country, particularly in the troubled northern region. At least 1,400 children have been abducted from their schools over the last year and about 200 of them have yet to be released, UNICEF said in September.

Sixteen children have died in the attacks, UNICEF Nigeria Representative Peter Hawkins also told The Associated Press.

Many schools across northern Nigeria remain shut over the crisis as governors battle to find a solution. With school resumption fast approaching, UNICEF has said at least 1 million children are afraid to return to their classrooms because of insecurity. That worsens Nigeria's education crisis with more than 10 million children already out of school.

Moreover, some of the freed captives have told the AP of how they continue to face trauma after their freedom with little or no support for their healthcare from the government. In Kaduna, more than 20 students released after nearly two months in the custody of gunmen are now seeking overseas education, The AP has reported.

The first mass school abduction in Nigeria was in 2014 when Boko Haram extremist rebels seized 276 girls from a school in Chibok, drawing international outrage. Local authorities believe that the Jihadi group may be aligning with the armed groups in carrying out some of the attacks in Nigeria's north.

Nnamdi Obasi of the International Crisis Group said authorities must improve the security presence and resources in the region as a first step in addressing the challenge. “Clearly the security operatives are outnumbered by the armed groups,” he said.