A massive truck bomb devastated the heavily guarded Marriott Hotel in Pakistan's capital today, engulfing the building in flames, killing at least 40 people and wounding at least 100.
The Marriott in Islamabad is a favourite place for foreigners as well as Pakistani politicians and business people to stay and socialise, despite repeated militant attacks.
The blast left a vast crater, some 30ft deep in front of the main building, where flames poured from the windows and rescuers ferried a stream of bloodied bodies from the gutted building.
Police sought in vain to shoo away bystanders and reporters for fear of gas leaks and that the building might collapse.
Leaders of Pakistan's civilian government, which have been vowing to continue and strengthen their country's seven-year alliance with the United States to combat terrorism and extremism, held that line.
President Asif Ali Zardari and prime minister Yousuf Raza Gilani strongly condemned the attack in a statement.
"This is terrorism and we have to fight it together as a nation," Rehman Malik, the head of Pakistan's interior ministry, told reporters at a hospital overflowing with the wounded.
Witnesses and officials said a large truck rammed the high metal gate of the hotel at about 8pm local time (2pm GMT), when the restaurants would have been packed with diners.
Senior police official Asghar Raza Gardaizi said rescuers had counted at least 40 bodies at the scene and 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.
Witnesses spoke of a smaller blast followed by a much larger one.
A US State Department official using a section of white pipe as a walking stick led three colleagues through the rubble from the charred building, one of them bleeding heavily from a wound on the side of his head.
One of the four, who identified himself only as Tony, said they had begun moving toward the rear of the Chinese restaurant after the first blast when the second one threw them against the back wall.
"Then we saw a big truck coming through the gates," he said. "After that it was just smoke and darkness."
Ambulances rushed to the area, picking their way through the charred carcasses of vehicles that had been in the street outside. Windows in buildings hundreds of metres away were shattered.
Mohammad Sultan, a hotel employee, said he was in the lobby when something exploded, he fell down and everything temporarily went dark.
"I didn't understand what it was, but it was like the world is finished," he said.
There was no immediate claim of responsibility for the blast.
But Pakistan has faced a wave of militant violence in recent weeks following army-led offensives against insurgents in its border regions.
The capital has not been spared, though today's blast appeared to be one of the largest-ever terrorist attacks in the country.
In July, a suicide bombing killed at least 18 people, most of them security forces, and wounded dozens in Islamabad as supporters of the Red Mosque gathered nearby to mark the anniversary of the military siege on the militant stronghold.
In June, a suicide car bomber killed at least six people near the Danish Embassy in Islamabad. A statement attributed to al Qaida took responsibility for that blast, believed to have targeted Denmark over the publication of cartoons depicting the Prophet Mohammed.
In mid-March, a bomb explosion at an Italian restaurant killed a Turkish woman in the capital, and wounded 12 others, including four FBI officials.