LAGOS, Nigeria — Hundreds of Nigerian students are missing after gunmen attacked a secondary school in the country’s northwestern Katsina state, police have confirmed.

The Government Science Secondary School in Kankara was attacked Friday night by a large group of bandits who shot “with AK 47 rifles,” Katsina State police spokesman Gambo Isah said in a statement.

Police engaged the attackers “in a gun duel which gave (some of) the students the opportunity to scale the fence of the school and run for safety,” Isah said.

About 400 students are missing, while 200 are accounted for, Isah said. The school is believed to have more than 600 students.

“The police, Nigerian Army, and Nigerian Air Force are working closely with the school authorities to ascertain the actual number of the missing and/or kidnapped students,” said Isah.

“Search parties are working with a view to find or rescue the missing students,” he said.

A resident of the town, Mansur Bello, told The Associated Press that the attackers took some of the students away.

The military, supported by airpower, has located the bandits’ enclave in Zango/Paula forest in the Kankara area, and there have been exchanges of gunfire in an ongoing operation, said President Muhammadu Buhari, according to a statement issued by presidential spokesman, Garba Shehu.

“Our prayers are with the families of the students, the school authorities and the injured,” said the president’s statement. The statement did not say if any student has been rescued.

This is the latest attack on a school by gunmen in Nigeria.

The most serious incident occurred in April 2014, when members of the Jihadist group Boko Haram kidnapped 276 girls from their school dormitory in Chibok, in northeastern Borno State. About 100 of the girls are still missing.

The latest attack is believed to have been carried out by one of several groups of bandits active in northwestern Nigeria. The groups are notorious for kidnapping people for ransom.