Hours after a suicide attack killed eight people, Pakistan's prime minister said in an Independence Day speech Thursday that the country must defeat extremism to survive.

As investigators sifted through the bloodied attack site in the eastern city of Lahore, and a military operation continued against insurgents in a northwest tribal region, Yousuf Raza Gilani admitted Pakistan "is passing through a difficult phase."

"We have to fight back the challenges of terrorism and extremism," the premier told an audience in the nation's capital, Islamabad. "The war against terrorism and extremism is the war of our own survival. With the people's cooperation we will fight this war and ensure the government's writ at all costs."

At least 18 people also were wounded in the Lahore attack, which occurred just before midnight Wednesday as Pakistanis poured into the streets to celebrate the nation's 61st anniversary of its independence from Britain.

The bomber struck outside a mosque under police guard, leaving a gory scene of blood-soaked police uniforms, shoes and pieces of metal apparently from the bomb. The attack took place near a police station.

Investigators combing the site found body parts believed to belong to the attacker, including an intact face, said police official Suhail Chaudhry. The attacker appeared to be a man in his 20s, Chaudhry said.

Of the dead, two were police, and six were civilians, he said. Of the wounded, 12 were police and six were civilians. Two wounded police were in critical condition, Chaudhry said.

Security forces are frequent targets of suicide attackers in Pakistan, where militancy is raging but has primarily been concentrated in the northwest, particularly the tribal regions bordering Afghanistan, where Taliban and Al Qaeda-linked fighters are based.

No one immediately claimed responsibility for the Lahore bombing, but it came a day after Pakistani Taliban militants said they were behind an explosion that struck an air force vehicle, killing up to 14 in the northwestern city of Peshawar.

A Taliban spokesman said Tuesday's attack was revenge for Pakistani military operations against militants in the frontier region near Afghanistan.

The spokesman, Maulvi Umar, said it was an "open war" between the militants and the armed forces, and threatened more attacks if the offensives did not stop.

Residents in the Bajur tribal region said Thursday that overnight, military planes and helicopters again bombed and shelled suspected militant targets.

The operation in Bajur has lasted about a week and displaced thousands. Death tolls have been impossible to verify, but so far the military has said at least 150 militants and nine paramilitary troops have died. Witnesses have separately reported handfuls of civilians deaths, but no official totals have been released.

Residents said militants have at times blocked routes and imposed curfews, preventing people from fleeing to safety. Rehmat Khan, a resident of Bajur's Mamund area, said some militants asked women and children to stay home and send their men with weapons to fight.

"They said this is the final round between Islam and infidels so everybody should take part in it," he said.

During his speech Thursday, Gilani also said that Pakistan has emphasized to the United States that it "cannot allow any unilateral action on Pakistani soil."

Late Tuesday, a suspected U.S. missile strike in South Waziristan killed at least nine alleged insurgents, including foreigners — the latest in a series of such strikes in the tribal belt.

Intelligence officials said the camp is linked to the group of Afghan warlord Gulbuddin Hekmatyar, whose followers are fighting U.S. and NATO forces in Afghanistan. They said Arabs and Turkmen were among the dead.