ABUJA, Nigeria — Gunmen attacked and kidnapped students taking secondary school examinations in conflict-battered Borno state in northeastern Nigeria, police said Monday.

The attack happened Monday morning at the Lassa Day Secondary School in the Askira-Uba area of Borno. Police spokesman Nahum Daso told The Associated Press that hours after the attack 10 people were rescued.

Secondary students are typically between 15 and 18 years old.

No group immediately claimed responsibility for the attack but an insurgency in the region has killed thousands and displaced millions.

“For now, we don’t have the number of how many students were abducted. We have about 10 victims who have been rescued,” Daso said, without mentioning casualties.

Rights group Amnesty International Nigeria said two teachers and a student were killed in the attack.

“Schools should be places of safety, and no child should have to choose between their education and their life,” the rights group said in a statement posted on its social platforms.

“The protection of children’s lives is paramount, and the Nigerian government has a duty to ensure that the country’s educational sector is not further threatened by armed groups on rampage across northern Nigeria.”

Boko Haram and its splinter faction, which is affiliated with the Islamic State group and known as Islamic State West Africa Province, or ISWAP, are prominent militant groups in northeast Nigeria and the greater Lake Chad area, which is bordered by Chad, Niger Republic and Cameroon.

Earlier this month, the Nigerian army rescued more than 300 people abducted by Boko Haram from Ngoshe, a town about 114 kilometers (71 miles) from Lassa, where Monday’s abduction happened.

In May, the West African country said its joint operation with the United States had killed 175 ISWAP fighters.

An insurgency in Nigeria’s northeast has killed thousands of people and displaced millions, according to the United Nations.