Schoolchildren were abducted in north-west Nigeria's Zamfara state, a spokesman for the state governor said on Friday.
He declined to say how many children were taken or provide further details.
A teacher from the region told AFP that hundreds of girls were abducted.
"More than 300 girls are unaccounted for after a head count of remaining students," said a teacher at the Government Girls Secondary School in Jangebe.
A parent told AFP he received a call about the incident.
"I'm on my way to Jangebe. I received a call that the school was invaded by bandits who took away schoolgirls. I have two daughters in the school," said Sadi Kawaye.
Police have not yet confirmed the incident.
This is the second such kidnapping in a little more than a week in northern Nigeria, where a surge in armed militancy led to widespread and worsening security problems.
Last week, gunmen killed a pupil in an overnight attack on a boarding school in the north-central Nigerian state of Niger and kidnapped 42 people, including 27 pupils.
The hostages have not yet been released.
In December, more than 300 boys were kidnapped from a school in Kankara, in President Muhammadu Buhari's home state of Katsina, while he visited the region.
The boys were released after negotiations with government officials but the incident caused global outrage.