The dead included three young girls who were students of grades 6, 7 and 10.
The sources from the district told Xinhua that the assailants fled the scene after seizing the cop’s submachine gun.
The prime minister’s office said the first tranche of nearly $1.1 billion U.S. would be released immediately.
General elections were supposed to be held within 90 days of the dissolution of assemblies.
The blast occurred on Sunday at a political event attended by the conservative Jamiat Ulema-e-Islam (JUI-F) party members in Pakistan’s northwestern Bajaur district.
Secret trials under the controversial army laws mean little transparency and a long, complicated process of appeals in the civilian courts.
The block on Wikipedia last week triggered an outcry, and many people condemned the move on social media.
General Asim Munir, who had previously led the country’s intelligence services, would replace outgoing Army Chief Qamar Javed Bajwa.
Authorities declared a national emergency as death toll from the months of flooding continues to rise.
