According to the political administration, the blast occurred during a football match which killed four people on the spot.
Initial reports have suggested that explosives were planted along roadside, which blew off with a powerful boom.
AFP adds: The incident happened at the Hussaini ground, owned by the local Shiite community in the Kalaya neighbourhood of the Orakzai tribal district.
Local administration official Zubair Khan gave the death toll which was confirmed by Khaista Akbar, another senior administration official.
“Eight people have been injured in the blast, two of them are in critical condition,” Akbar told AFP.
He said the bomb was apparently dug into the ground before it exploded.
Nobody has yet claimed responsibility but militants linked to the Taliban and Al-Qaeda have targeted the country’s Shiite minority in the past.
Earlier on Sunday a US drone strike targeting a Taliban-linked warlord killed at least six militants in another tribal district, North Waziristan, Pakistani security officials said.
Pakistan has strengthened its own offensive against the Taliban since their attack on a military-run school on December 16 killed 150 people, 134 of them children.
Prime Minister Nawaz Sharif has announced the establishment of military courts for terror-related cases, and the premier has reinstated the death penalty for such cases.
In November last year a suicide blast ripped ripped through crowds gathered to watch a volleyball game in eastern Afghanistan. A total of 57 people were killed.