A senior police official said the target of the bombing appeared to be Brigadier Khalid Javed, the second most senior officer in the Frontier Corps force, who escaped unhurt.
City police chief Ijaz Khan who visited the spot of the bombing said "five people including an FC solider were killed. A woman and a child were also among those killed."
29 people were also injured in the suicide blast attack.
Bomb disposal squad official Shafqat Malik said 45 kilogrammes of explosives were used in the blast. He said mortar shells were also put in with the explosives to increase the impact of the blast.
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Television footage showed the wreckage of the car used for the suicide bombing.
An emergency was declared at Lady Reading hospital here.
Security forces reached the spot soon after the incident, cordoned off the area and started their initial investigation.
President of Awami National Party Asfandyar Wali Khan also condemned the blast.
The Pakistani Taliban faction led by Maulanah Fazlullah claimed responsibility for the attack, vowing revenge against the ruling Pakistan Muslim League Nawaz (PML-N) for a military operation in the northwest.
More than 1,000 militants have been killed in the operation.
Meanwhile, at least 42 militants were killed when Pakistani military jets pounded militant hideouts in the restive North Waziristan province, the army said today.
Military jets targeted militant hideouts in Dandi Kachkol, Gurbaz and Mana areas of North Waziristan and killed 19 militants, the army said in a statement.