Seven students, four security officials, two watchmen and a journalist were among those injured. Mehsud said the terrorists had links inside Afghanistan.
Inter Services Public Relations (ISPR) has said that security forces reached the site and successfully completed the operation killing all the suspected militants. A security guard was shot and gravely wounded in the attack.
A gunbattle continued between forces and the attackers for over an hour and the Pakistan Army successfully killed all the terrorists.
Tehreek-e-Taliban Pakistan, the Pakistani Taliban, has already claimed responsibility for the attack.
The injured, including a station house officer (SHO), constable, army soldiers and students, have been shifted to Khyber Teaching Hospital and CMH for treatment.
"Our mujahids have attacked the building because it was used as office for ISI". "I rushed to the door and saw a fountain of blood pumping out of the shoulder of my roommate who was standing outside the room", he said.
The army and local police who were summoned to the scene killed all the attackers, who arrived at the Agricultural Training Institute on Friday by rickshaw, the military's press wing said.
Wali and another student rushed to his aid, hiding from the gunmen for nearly an hour before they were rescued by security forces.
"We were sleeping when we heard gunshots".
Around eight to 10 people were reportedly evacuated by the security officials.
Violence erupted over the weekend after police and paramilitary forces launched a bungled attempt to clear a sit-in, igniting fresh demonstrations in cities across the country, including in Lahore and Karachi.
The protests were finally ended just days ago under a military-brokered deal.
In 2014, Pakistani Taliban gunmen murdered more than 140 children in Peshawar, according to the BBC, making it one of the deadliest attack in the country's history.