Police in Nigeria have launched a search and rescue operation for 317 girls kidnapped from a school in the state of Zamfara.
The operation comes as 42 people kidnapped from a boarding school in a similar incident last week in Niger state were released.
The kidnappings are carried out for ransom and are common in the north.
President Muhammadu Buhari condemned the latest kidnapping as “inhumane and totally unacceptable”.
The United Nations Children Fund also condemned the abduction of the girls and called for their safe release.
Nigerian police said in a statement that “a co-ordinated search and rescue operation, involving the deployment of both ground and aerial assets” was under way.
Two helicopters have been deployed.
Police also appealed for calm. Residents of the town of Jangebe, where the abduction took place, have reacted angrily, attacking vehicles that entered.
The Vanguard newspaper said that a convoy of journalists was attacked by a mob.
Friday’s attack happened at 01:00 local time (midnight GMT) when a group of gunmen arrived at the Government Girls Secondary School in Jangebe.
Some reports say the girls, aged 12 to 16, have been taken to the Dangulbi forest.
Zamfara state has closed all boarding schools.
No group has so far admitted carrying out the attack.