File Photo: Schoolchildren kidnapped from an Islamic seminary three months ago walk from a van as they are reunited with their parents in Minna after their gunmen captors freed them from forest hideouts. AFP
More than 1,400 children were abduted in Nigeria last year according to the United Nations, mostly during attacks on schools and colleges by gunmen known locally as "bandits".
Students are often quickly released after ransom payments but 200 were still missing in September, the UN added.
Thirty students of Federal Government College and one teacher have arrived in Birnin Kebbi "following their release," Yahaya Sarki, a spokesman for the Kebbi state governor, said late Saturday.
"They shall undergo medical screening and support while being reunited with their families," he added in a statement.
It was unclear if ransom was paid for the release of the students or if any others were still in captivity.
Last June, gunmen stormed the college in the town of Yauri, seizing 102 students and eight staff according to the school.
The attack was confirmed by police but they would not say how many students or teachers were taken.
Security personnel rescued eight of the kidnapped students and a teacher while bodies of three students were found in the bush.
The kidnappers freed 27 students and three staff in October, while an unspecified number were released after their parents negotiated with the captors.
Clashes between herders and farmers over access to land has plagued northwest and central Nigeria for years, with some groups evolving into criminal gangs who now terrorise local communities.
Since last year, gangs have intensified highway kidnappings and mass abductions of students.
On Wednesday, the Nigerian government issued an official gazette declaring activities of bandits as "acts of terrorism."
President Muhammadu Buhari, a former army general, is also battling a more than decade long jihadist insurgency in the northeast and separatist tensions in the country's southeast.