ISLAMABAD ? A suicide bomber walked up to a checkpoint and blew himself up near a major Pakistan Air Force base Friday, killing at least six people and wounding another nine, police said.

The incident took place in the town of Kamra, some 80 kilometers (50 miles) west of Islamabad near the Pakistan Aeronautical Complex (PAC).

"It was a suicide attack, which killed six people including four civilians and two Pakistan Air Force personnel," district police chief Fakhar Sultan told Agence France-Presse.

Nine people were also wounded in the attack, he added. The identities of the wounded were not immediately clear.

The attacker blew himself up when he was stopped at a security checkpoint on the main road used by both civilians and air force personnel, Sultan said.

"We have found a mutilated face, as well as other body parts, including legs and arms of the bomber," he said.

There was no immediate claim of responsibility but a deluge in attacks blamed on Taliban and Al-Qaeda-linked extremists that has left more than 190 people dead this month in the frontline state in the US-led "war on terror."

The military has been a major target. On Thursday, gunmen killed a brigadier working in a UN peace mission in Sudan with his driver in Islamabad.

On October 10 militants staged an audacious ambush on the army headquarters in Rawalpindi claimed by the Tehreek-e-Taliban in Pakistan (TTP) movement.

Pakistan has vowed to crush the network, unleashing a major ground and air offensive targeting TTP in their South Waziristan stronghold along the Afghan border, where al-Qaeda is accused of plotting attacks on the West.

Pakistan is on heightened alert for attacks, with the military pressing a major offensive against the TTP's estimated 10,000 fighters in South Waziristan, part of a lawless tribal belt.

Prime Minister Yousuf Raza Gilani condemned the Kamra attack and vowed that the government would not waver in its resolve to "root out terrorism."

Millions of students have been kept at home this week as Pakistan shut all schools and colleges after a suicide attack Tuesday at a university.

Officials say more than 150 people, at least 137 militants and 18 soldiers, have been killed since the South Waziristan offensive began Saturday and more than 120,000 civilians have fled the war zone.

A vanguard of troops have established footholds and are thrusting into the second phase of the operation, backed by helicopter gunships and warplanes, to home in on Taliban strongholds, a military official told Agence France-Presse Thursday.

There was heavy fighting in Kotkai, the hometown of TTP chief Hakimullah Mehsud and between Taliban-stronghold Sararogha and Jandola, the site of a large military base, where the army said 13 militants were killed.