By Rafiu Ajakaye 

LAGOS, Nigeria

Eight terror suspects have been arrested by the Nigerian police, including a man believed to be the head a Boko Haram sleeper cell in the northwestern Kano state as the mastermind of a mass killing in 2013.

Tony Opuiyo, spokesman of the country's department of state service, or the secret police, said in a statement on Monday that the suspects were arrested following surveillance targeted at halting terrorist activities.

“The service arrested one Mudaisiru Jibrin aka Namakele/Alarama on 17 July, 2016, at Sauna quarters, Yankaba area in Kano. Jibrin was the spiritual leader of a newly uncovered Boko Haram cell in Kano,” said the statement.

“Preliminary investigation so far conducted revealed that he was also the mastermind of the shooting of some students at a Government Secondary School (GSS), in Mamudo village near Potiskum, Yobe State, in 2013,” it added. Some 30 people were killed in the attack.

The statement said four other Boko Haram operatives - Mukhtar Tijani, Isiaku Salihu, Abdullahi Isah and Hindu Isah - were also arrested on July 8 in the neighboring Kaduna state.

It added: “In a related development, on 12 August 2016, at Auchi in Edo state, three members of the Ansaru terrorist group hibernating in Kogi state were apprehended by the service. Usman Abdullahi, Abdulmumuni Sadio and Ahmad Salihu were arrested while making arrangements to launch attacks on some selected targets in Edo and Kogi states, before escaping to join ISIS in Libya.”

Ansaru is believed to be an independent jihadist movement with a similar agenda as Boko Haram, although experts say there is proof of their occasional collaboration such as the attack on the United Nations building in August 2011.