Two suspects have been arrested by Nigerian police in connection with the kidnapping of students from a Nigerian college last year, one of the most high-profile cases in a recent run of pupil abductions.

Gunmen killed a member of staff as they stormed Greenfield University in northwestern state of Kaduna on April 20, 2021, before seizing around 20 students.

Five of the hostages were killed a few days later to force families and the government to pay a ransom. Fourteen were released after 40 days in captivity.

The Nigerian police said late Wednesday they had detained two suspects — Aminu Lawal, also known as Kano, and Murtala Dawu, otherwise known as Mugala — who were implicated in several abduction cases.

“They equally confessed to the kidnap of students from the Greenfield University in Kaduna State, and the mindless murder of five victims before the payment of ransom, and eventual release of the others,” said national police spokesman Olumuyiwa Adejobi in a statement.

He said the suspects would be arraigned in court after investigation.

Heavily-armed criminal gangs have become an increasing security threat in northwest and central Nigeria, pillaging villages, raiding cattle and kidnapping for ransom.

Recently, the gunmen have turned their focus to rural schools and universities, where they kidnap students or schoolchildren.

Around 1,500 schoolchildren were seized last year in 20 mass kidnappings in schools across the region, with 16 students losing their lives, according to the UN’s child welfare agency UNICEF.

Kidnap victims are usually released shortly after during negotiations with local authorities, though state officials always deny that any ransom payments are made.

Mass kidnappings in the northwest are adding to President Muhammadu Buhari’s security concerns, which include a more than decade-long Islamist insurgency in the northeast.