Islamabad. A candidate running for Pakistan’s national assembly at historic polls next week has been shot dead, police have said.Police said that Sadiq Zaman Khattak, the Awami National Party (ANP) candidate, had been shot dead on Friday along with his three-year-old son in Karachi."He was returning from a mosque after saying his Friday prayers with his three-year-old son when gunmen on a motorbike opened fire,” police spokesman Imran Shaukat told AFP news agency.Al Jazeera’s Kamal Hyder, reporting from Islamabad, said that Khattak’s son died of his wounds in hospital and the Tehreek-e-Taliban, Pakistan’s umbrella Taliban factionm, had claimed responsibility for the shooting."That’s why the election in that particular constituency in the city of Karachi, in the area of Korangi, has been postponed,” Hyder said.Five injured Police said that five people, including two guards of the slain ANP candidate, were injured.It is the first time that a national assembly candidate has been killed in Pakistan’s election campaign. Campaigning has been marred by Taliban threats and attacks, which have killed 62 people since April 11, according to an AFP.Khattak was a candidate for the ANP, the leading secular party in Pakistan’s ethnic Pashtun northwest.A senior party leader said he had received threats.However, Hyder said all parties agreed that the election would go ahead, no matter what the cost was.