The blast sparked panic at the rally. It was not immediately known if a bomb had been planted at the venue or the blast was triggered by a suicide attacker, officials said. The injured were rushed to a nearby hospital. In December last year, 54 people were killed and over 100 injured when a suicide attacker blew himself up in a packed mosque in Charsadda in a bid to target former minister Aftab Ahmed Khan Sherpao.