Pakistan: Will the center hold?

Update: 1:27 Taliban claim responsibility. Arrests have been made.

Pakistan headed for a power vacuum? Suicide bombers hit weapons complex, the question is - is it a nuclear weapons complex? Death toll now at 70

The bombings hit one of Pakistan's most sensitive military installations and underlined the threat posed by Islamic militants to the Muslim world's only nuclear-armed nation as well as its war-ravaged neighbor, Afghanistan.

Workers were streaming through the gates of the tightly guarded factory in Wah, 20 miles west of Islamabad, during a shift change when the two bombs exploded. The force of the explosions knocked many people to the ground and sprayed others with shrapnel.

"I looked back and saw the limbs of my colleagues flying through the air," said Shahid Bhatti, 29, his clothes soaked in blood.

"It was like a doomsday," said Ghaffar Hussain, whose nephew was killed. "We are finished, we are ruined," he said, tears rolling down his face.

Prime Minister calls threat "unprecedented and appealed to lawmakers to come together to formulate a "national strategy on terror." But the Islamists are fighting amongst themselves and the coalition is "veering towards collapse".

The terrorists are belligerent and bellicose as usual.

Maulvi Umar, a spokesman for Pakistani Taliban groups, told The Associated Press that the arms factory attack was to avenge airstrikes on militants in Bajur, an extremist stronghold in the mountainous frontier region.

More bombings will be carried out in major cities, including the capital and the southern metropolis of Karachi, unless the offensives are halted, he said.

The markets are jittery.

Pakistan's stock market, which rose for six consecutive years to 2007, and was one of the best-performing markets in Asia in that period, has fallen about 27 percent this year.