The suicide attacker with explosive-laden motorcycle hit the Frontier Constabulary (FC) convoy at a traffic signal in Peshawar's Hayatabad area, police said.
Three FC men, including a major, were killed in the attack, Superintendent of Police Imran Malik said.
Nine people, including two security personnel, were injured in the blast, Malik added.
SSP (operations) Sajjad Khan said 10-12 kilograms of explosives were used by the bomber, who was riding the bike.
Two vehicles that were part of the convoy were completely damaged in the blast.
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Tehrik-e-Taliban Pakistan (TTP) claimed responsibility for the attack.
TTP spokesman Muhammad Khurasani in a statement mailed to media said slain Major Jamal Sheren was on their hit list.
The terror group vowed to carry out more attacks on FC troops.
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.