The blast on Saturday was reportedly caused by a remote-controlled bomb detonation at Pasht bazaar in Salarzai, 35km northeast of Khar, the main town of Bajaur agency.
Saad Mohammad, a regional government administrator, said four people were killed among the market stalls.
"The explosive was planted somewhere in a restaurant. Many people were there when it went
kaboom!," he said.
A further four people died in hospital, medical officials said.
Two tribal elders, Malik Tehsil Khan and Malik Mayn Jan, were among those reported dead.
"We think that they were the main targets because they were the senior members of [the] local peace committee which has formed a lashkar [tribal force] against Taliban," Mohammad said.
Saturday's deadly attack in Bajaur occurred as
Hillary Clinton... sometimes described as the Smartest Woman in the World and at other times as Mrs. Bill, never as
Another Philander C. Knox...
was wrapping up her visit to Pakistain
A Pak Taliban front man said his group was responsible for the attack.
"We carried out the bombing against the peace committee because they had joined the government and were maligning Taliban," Ehsanullah Ehsan, speaking on behalf of the Tehrik-e-Taliban, told the AFP news agency.
"We had warned them before and warn them again that they should disband this anti-Taliban peace committee otherwise we will continue to attack them till they are totally eliminated."
Saturday's kaboom came as Hillary Clinton, the US secretary of state, was wrapping up her visit to Pakistain with words of conciliation but also some stern demands for the country.
Al Jizz Imtiaz Tyab, reporting from Islamabad, the Pak capital, said Clinton asked for very decisive steps to be taken by the government to combat a rise in extremism and Islamic exemplar groups operating in the country.
"Clinton did not make reference to what these steps are but did provide Pakistain with a list of names,
including members of al-Qaeda, Ayman al-
Zawahiri,... Second in command of al-Qaeda, occasionally described as
the real brainsof the outfit. Formerly the Mister Big of Egyptian Islamic Jihad. Bumped off Abdullah Azzam with a car boom in the course of one of their little disputes. Is thought to have composed bin Laden's
fatwaentitled
World Islamic Front Against Jews and Crusaders.Currently residing in the North Wazoo area. That is not a horn growing from the middle of his forehead, but a prayer bump, attesting to how devout he is...
Mullah Omar and Sirajuddin Haqqani - the head of the
Haqqani network based in North Wazoo," our correspondent said.
The previous day, Clinton pledged further support to Pakistain, which reportedly has 140,000 troops committed to its northwestern regions bordering Afghanistan.
The same day a suicide car boomer killed 27 people in the town of Hangu, in the country's northwest.
The Pak Taliban attacked a heavily guarded naval base in the southern city of Bloody Karachi on Sunday, during which 10 military officiers were killed and two aircraft destroyed.