Violence erupted after former interior minister Mohamed Bazoum was declared winner of Sunday’s runoff vote.
Gunmen in Nigeria have released 42 people, including 27 students, who were kidnapped from a boarding school last week in the north-central state of Niger, the state’s governor said.
Their release comes just a day after a separate raid on a school in Nigeria’s Zamfara state where gunmen seized more than 300 girls.
Kidnappings for ransom by armed groups, many of whom carry guns and ride motorcycles, are common across many northern Nigerian states.
Last week, 27 students, three staff and 12 members of their families were abducted by an armed gang who stormed the Government Science secondary school in the Kagara district of Niger state at around 2am local time, overwhelming the school’s security detail.
One boy was killed during the raid.
“The Abducted Students, Staff and Relatives of Government Science Collage Kagara have regained their freedom and have been received by the Niger State Government,” Governor Abubakar Sani Bello said in a tweet.
Al Jazeera’s Ahmed Idris, reporting from Abuja, said their release followed days of tense negotiations between the government of Niger state and the government and federal forces.
“They spent at least 9-10 days in captivity, and at some point a lot of people gave up that anything good will come out of these negotiations,” he said.
Idris said the government was not saying whether it had paid a ransom, after previously ruling out such a move.
“But we understand that the bandits demanded the release of at least six of their members held in police custody. Banditry and kidnapping has become the biggest criminal enterprise now growing fast across Nigeria,” Idris said.
The recent attacks have raised concern about rising violence by armed gangs and groups and in Nigeria. Armed group Boko Haram carries out abductions in Nigeria’s turbulent northeast, as does a branch of the ISIL (ISIS) group.
The unrest has become a political problem for President Muhammadu Buhari, a retired general and former military ruler who has faced mounting criticism in recent months over high profile attacks by the gangs known locally as “bandits”.
Buhari replaced his longstanding military chiefs this month amid worsening violence in Nigeria.
Violence and insecurity have compounded the economic challenges faced by citizens in Africa’s most populous country and top oil exporter, which is struggling to cope with a fall in revenues due to a slump in crude prices in addition to the effect of the COVID-19 pandemic.