The incident occurred when the bomber entered the Arbab Niaz stadium stadium in Pardah Bagh (women park) area and fired gunshots.
Witnesses said security personnel opened retaliatory fire upon which the bomber detonated his explosives near a mosque inside the stadium where a government-run camp was set up for tribal refugees.
The intensive blast caused one of mosque's walls to fall down and nearby buildings were also damaged.
The bomber was believed to have been targeting a group of Internally Displaced Persons (IDPs) from Tirrah Valley of the troubled Khyber tribal region who had gone to the camp in the stadium to get themselves registered for ration and repatriation.
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The bomber entered the stadium posing as an IDP and then detonated his jacket containing eight to 10 kg of explosive material.
Thousands of people from Tirrah valley fled their homes after the military began an operation against al-Qaeda- affiliated militant organisation in 2011.
Hospital sources confirmed that five persons were killed in the blast. Children were also among the 14 injured.
The Bomb Disposal Squad reached the blast site and cordoned off the area as a probe into the incident was conducted.