A suspected suicide bomber killed six people on Monday in an attack on a group of political workers canvassing for Feb. 18 parliamentary polls in Pakistan's restive tribal region of North Waziristan, witnesses said, according to Reuters. An independent candidate, Nisar Ali Khan, contesting for a National Assembly seat in the region escaped unhurt, but nine of his supporters were wounded in the attack near Mir Ali, a town frequented by Taliban and al Qaeda fighters. "We were having a meeting at a roadside place with Nisar and his supporters when the explosion occurred," said Haji Nakim Khan, a tribal leader, who was among the wounded. "We found severed legs at the site of attack, so we think it was a suicide attack." Though independent, Khan was aligned to the Awami National Party (ANP), a secular party representing ethnic Pashtuns in North West Frontier Province. There was no immediate official confirmation of the incident, which came two days after another suicide bomber killed 16 people and wounded 25 at an ANP election rally in the northwestern town of Charsadda. Violence has intensified in Pakistan in the run-up to an election that was due to be held on Jan. 8, but was delayed until Feb. 18 after the assassination of opposition leader Benazir Bhutto in gun and suicide bomb attack on Dec. 27. More than 400 people have been killed in clashes between troops and militants and bomb and suicide attacks since the start of the year, raising security fears in the nuclear-armed country. The government has blamed an al Qaeda-linked militant leader, Baitullah Mehsud, who is based in South Waziristan, for the attack on Bhutto and many other attacks across the country.