Pakistani army troops arrive at its headquarters to take positions after attack by gunmen at army's headquarters in Rawalpindi, 10 Oct 2009Pakistani military officials say six gunmen attacked the army'sheadquarters near the capital in Rawalpindi Saturday.  Authorities sayfour of the attackers were killed.  Security forces are searching forthe other two who managed to escape.  At least six troops died in theassault.

Security officials say the gunmen, disguised inmilitary uniforms, drove up shortly before noon Saturday in a van tothe heavily guarded army headquarters.

The attackers opened fireat the checkpoint outside the compound and threw at least one grenade,triggering a gun battle with security forces.

Authorities quickly sealed off the roads leading to the army headquarters.

Pakistani army helicopters fly over headquarters after attack by gunmen in Rawalpindi, 10 Oct 2009 At least three helicopters circled overhead.  Occasional gunfire rang out in the area.  Ambulances rushed to the scene.

No one has claimed responsibility for the attack.

Earlierthis week, a suicide bomber disguised in a paramilitary uniformexploded inside the World Food Program's headquarters in nearbyIslamabad, killing five people.

The Pakistani Taliban claimedresponsibility and threatened to target other internationalorganizations and Pakistani government and military locations.

OnFriday, at least 50 people died in a suicide attack in the northwesterncity of Peshawar.  No one claimed responsibility, but Pakistani leadersblamed the Taliban and vowed to start a new offensive against militantsin the country's tribal regions.

Pakistani Information MinisterQamar Zaman Kaira told reporters Saturday that such attacks show themilitants are worried about the military focusing its offensive ontheir stronghold in the South Waziristan tribal region.

"Now theterrorists are on run," he said. "They are frustrated now andthat is why they are targeting our security forces, our civilianpeople, the government installations, so that to discourage thegovernment, the security forces and the people of Pakistan."

ThePakistani military has not publicly set a date for any major operationalong the Afghan border.  But U.N. officials in Pakistan say some80,000 civilians have fled the area.