
The blast went off during the right-wing religious Jamiat Ulema-e-Islam (JUI) party rally for its candidate Munir Orakzai in a Pakistani tribal area.
Other reports said the number of victims might be higher, with Al Jazeera reporting 15 people killed.
The bomb was apparently planted near the main stage of the event, AP said quoting a local government official. Two JUI party leaders reportedly escaped from the scene unhurt. No one has immediately claimed responsibility for the attack.
The latest in the series of attacks targeting political parties and their candidates, it raises the number of Pakistani election campaign victims to more than 70, according to an AFP tally.
According to a hospital official, the number of causalities could rise as many people were in critical condition.
Rescuers and security forces rushed to the site and shifted the bodies and the injured to the hospital.
At the time of the blast, hundreds of people were present to listen to their leaders contesting for the country's May 11 elections.
The bomb exploded with a big bang at the conclusion of the public gathering near the stage where two JUI-F leaders were sitting but they remained unhurt in the attack.
The nature of the blast was not confirmed yet but a higher officer said that the blast was conducted with an improvised explosive device.
No group or militant organization has claimed responsibility for the attack yet.