Garba Shehu revealed this to BBC on Sunday, adding that the students in captivity were far fewer than the number staff members reported missing.
On Friday, the gunmen invaded Government Science Secondary School, Kankara, Katsina State, and took away some students.
While about 800 pupils were enrolled at the all-boys school, about half remain unaccounted for.
In the BBC interview, Shehu said there was a “massive deployment” of troops to rescue the abducted children.
He said: “Military commanders on the ground have the coordinates of where they believe the bandits are, and whoever they are holding. They have surrounded all of that area.”
BBC also reported that President Buhari, who comes from the state and is currently there on a private visit, was being briefed hourly on efforts to rescue the children, according to Garba Shehu.
“The criminal elements, bandits, will be crushed. They will be eliminated,” Garba added.
He added that the children believe that 10 of their schoolmates were taken by the bandits, but this still needed to be verified.
The report also noted that school authorities were speaking to parents to establish how many students have returned home and how many others could still be scattered across a large area after fleeing the attack.
Earlier, the state governor, Aminu Masari, on Sunday, said 333 students of the school were still missing. He had also ordered all boarding schools in the state shut.
Also, mothers of the students who went protesting, asking the government to rescue their children were dispersed with tear gas.[embedded content]