Kidnappings for ransom are common in Africa's most populous country, where heavily armed criminal gangs have targeted schools in the past, especially in the northwest, though such attacks had abated recently.
Local government officials in Kaduna State confirmed the kidnapping attack on Kuriga school on Thursday, but gave no figures as they said they were still working out how many children had been abducted.
At least one person was shot dead during the attack, local residents said.
Sani Abdullahi, one of the teachers at the GSS Kuriga school in the Chikun district, said staff managed to escape with many students when the gunmen, known locally as bandits, attacked early on Thursday firing gunshots in the air.
He told local officials that 187 pupils had been snatched from the main school along with 100 more from the school's primary classes.
"Early in the morning, before we got up, we heard gunshots from bandits, before we knew it they had gathered up the children," another local resident Musa Mohammed told the French news agency AFP.
"We are pleading to the government, all of us are pleading, they should please help us with security."
Local resident Muhammad Adam also told AFP more than 280 have been kidnapped. Two more residents said around 200 were abducted.
The abduction illustrates the complex security challenge facing President Bola Ahmed Tinubu, who, after coming to office in May, promised to make Nigeria safer and bring in more foreign investment.
Thursday's kidnapping also comes almost 10 years after Boko Haram extremists triggered international outcry by kidnapping more than 250 schoolgirls from Chibok in Nigeria's northeast.
Some of those girls are still missing.
No child left behind
Local officials and police did not give any figures for the Kuriga kidnapping. Often figures of those reported kidnapped or missing in Nigeria are lowered after people who fled an attack return home.
"As of this moment we have not been able to know the number of children or students that have been kidnapped," Kaduna State Governor Uba Sani told reporters in Kuriga on Thursday. "No child will be left behind."
Hundreds of schoolchildren and college students have been kidnapped in mass abductions in the country's northwest and central region, including in Kaduna, in the last three years.
Almost all were released for ransom payments after weeks or months spent in captivity in camps hidden in forests that stretch across northwestern states.
Amnesty International condemned the abductions in Kaduna.
"Schools should be places of safety, and no child should have to choose between their education and their life," the rights group said on X, formerly Twitter.
"The Nigerian authorities must take measures immediately to prevent attacks on schools, to protect children's lives and their right to education."
Nigeria's armed forces are battling on several fronts, including against armed criminals in the northwest and a long-running Islamist insurgency in the northeast of the country.
More than 100 people were missing after militants carried out a mass kidnapping last week targeting women and children in a camp for those displaced by the conflict in the northeast.
Last September, gunmen abducted more than 30 people, including 24 female students, in a raid in and around a university in northwest Zamfara State.
In February 2021, bandits raided a girls' boarding school in the town of Jangebe in Zamfara, kidnapping more than 300 students.
Between July 2022 and June 2023, 3,620 people were abducted in 582 kidnap-related incidents in Nigeria, according to local risk analysts SBM Intelligence.