The suicide attacker with explosive-laden motorcycle hit the Frontier Constabulary (FC) convoy at a traffic signal in Peshawar’s Hayatabad area, police said.
Two Frontier Corps men, including a major, were killed in the attack.
Ten others, including passersby, were injured in the blast near Bagh-e-Naran chowk in Hayatabad.
Two vehicles that were part of the convoy were completely damaged in the blast.
Security personnel cordoned off the area after the explosion as rescue services shifted the injured to Hayatabad Medical Complex.
There has been no immediate claim of responsibility for the blast.
The attack comes a day after the Pakistan army announced it had launched an operation in the Khyber tribal region to rout Islamic State militants.