ISLAMABAD, Pakistan - A massive suicide truck bomb devastated the heavily guarded Marriott Hotel in Pakistan's capital Saturday, killing at least 40 people and wounding at least 100. Officials feared there were dozens more dead inside the burning building.

The blast targeting the U.S. hotel chain appeared to be one of the largest terrorist attacks ever in Pakistan, leaving a vast crater some 30 feet deep in front of the main building, where rescuers ferried a stream of bloodied bodies.

The five-story Marriott had been a favorite place for foreigners as well as Pakistani politicians and business people to stay and socialize in Islamabad despite repeated militant attacks.

The attack came just hours after President Asif Ali Zardari made his first address to Parliament and days ahead of the new leader's meeting with President Bush Tuesday in New York on the sidelines of the U.N. General Assembly.

Rehman Malik, the head of Pakistan's Interior Ministry, told The Associated Press that authorities had received intelligence that there might be militant activity due to Zardari's inaugural address. Security had been tightened, he said.

Though there was no immediate claim of responsibility for the blast, Pakistani officials have warned that militancy could heat up following a wave of cross-border strikes on militant bases by U.S. forces in Afghanistan, which had angered public opinion.

"This is terrorism and we have to fight it together as a nation," Malik told reporters at a hospital overflowing with the wounded.

Witnesses and officials said a large truck had rammed the high metal gate of the hotel at about 8 p.m., when the restaurants would have been packed with dinners, including Muslims breaking the Ramadan fast.

Senior police official Asghar Raza Gardaizi said rescuers had counted at least 40 bodies at the scene and that he feared that there "dozens more dead inside."

Associated Press reporters saw at least nine bodies scattered at the scene. Scores of people, including foreigners, were running out — some of them stained with blood.

Two hospitals said 10 foreigners were among those in their treatment, including one each from Germany, Saudi Arabia, Morocco and Afghanistan.

A U.S. State Department official led three colleagues through the rubble from the charred building, one of them bleeding heavily from a wound on the side of his head.