The mastermind of this week's bombings in the Nigerian cities of Jos and Zaria, which killed at least 70 people, has been arrested by local troops, the defense ministry said Thursday, according to Reuters.

The man is reportedly suspected to have orchestrated the bombing in the central Nigerian city of Jos on Sunday and in the north-central city of Zaria on Tuesday. No group has claimed responsibility for the attacks, but authorities believe it was carried out by the Islamist extremist group Boko Haram, which has intensified its offensive since President Muhammadu Buhari took office in May.

"The highly placed terrorist was arrested with two others who were in his company. One of them was however shot while trying to escape," the defense ministry said, according to Reuters, but did not mention if the shooting was fatal.

The ministry reportedly said the suspect was arrested at a checkpoint in the city of Gombe, close to Boko Haram's stronghold in the northeast. Officials however did not reveal the identity of the suspects nor give details on why the military suspected them to have been behind the attacks.

One attack near a mosque and another in a Muslim-majority neighborhood in Jos killed at least 44 people, according to authorities, while the Zaria bombing hit a local government office, killing at least 26 people.

Since coming to power in May, Buhari has made tackling the militant group a priority, calling for major increases in security funding and bolstering the military campaign against the group. In March, the militant group, which is also active in neighboring countries, including Niger and Cameroon, pledged allegiance to the Islamic State group, giving rise to fresh concerns.

Last month, the United States condemned Boko Haram’s violent tactics and vowed greater support to Nigeria to fight the group.