Sergio Vieira de Mello, a 55-year-old veteran Brazilian diplomat who was nearing the end of his four-month mission as the U.N.'s top man in Iraq, was wounded and trapped in the rubble at the Canal Hotel, where the U.N was based. Hours later, the U.N. announced his death.
According to witnesses, a cement truck exploded at a concrete wall outside the hotel at around 4:30 p.m. The blast left a six-foot-deep crater in the ground, shredded the hotel's facade and stunned an organization that had been welcomed by many Iraqis in contrast to the U.S.-led occupation forces.
While the hotel was well guarded, the building next door, a hospital, was vulnerable, reports CBS News Correspondent Randall Pinskton. Someone managed to maneuver the truck bomb into a driveway, next to the U.N. headquarters.
The blast occurred during a U.N. press conference, ironically, on clearing leftover land mines to make Iraq a safer place. The scene was captured by CBS News cameraman Atheer Hameed, who kept filming despite the mayhem.
The video shows images of chaos and unimaginable horror. Everywhere, torn bodies and blood-soaked survivors with makeshift bandages; the stunned and wounded stumbling through the door, stepping over those unable to move.
Outside, they hold onto each other, shocked that the war had come to the United Nations. Medivac helicopters can be seen in the air, ambulances on the ground and an intense effort to find survivors in the rubble.
President Bush, at his ranch in Crawford, Texas, condemned the bombing, calling the attackers "enemies of the civilized world."
"These killers will not determine the future of Iraq," Mr. Bush said. "Every sign of progress in Iraq adds to the desperation of the terrorists and the remnants of Saddam's brutal regime."
The U.N. Security Council, which was briefed about the bombing at a closed-door meeting, called the blast a "terrorist attack."
"Those who killed him have committed a crime, not only against the United Nations but against Iraq itself," U.N. Secretary-General Kofi Annan said in a statement, calling Vieira de Mello "an outstanding servant of humanity."
It's still too early to pinpoint responsibility for the blast, reports CBS News Correspondent David Martin, but U.S. officials say there are three groups working to undo the American occupation and reconstruction of Iraq:
A senior U.S. official, speaking on condition of anonymity, said in Baghdad that the truck did not breach the security wall that was erected around the hotel within the past month. He said it was parked on an access road just outside the compound. Witnesses said it was uncertain if the truck was parked or trying to break through the barrier.
The official estimated the amount of explosives was double that used in the attack on the Jordanian embassy almost two weeks ago in which 19 people were killed.
The embassy attack was thought to be the first such terrorist-style bombing in the Iraqi capital since Saddam Hussein's fall.
L. Paul Bremer, the top U.S. civilian administrator in Iraq, walked through the scene of destruction as workers dug through the rubble with their hands trying to find people. There was a 15-yard wide hole in the ground.
Bremer had tears in his eyes and hugged Hassan al-Salame, an adviser to Vieira de Mello. A part of the building collapsed near him. People cried: "Watch out. Watch Out."
"We will leave no stone unturned to find the perpetrators of this attack," he said.
Among the dead were a Canadian and a Dane. One wounded man had a yard-long, inch-thick aluminum rod driven into his face just below his right eye. He identified himself as a security consultant for the International Monetary Fund, saying he had just arrived in the country over the weekend.
The Iraq posting capped Vieira de Mello's 30-year career as a U.N. troubleshooter in the world's most dangerous places, from Kosovo to Cyprus to East Timor. After being named to the Iraq post in June, the Brazilian diplomat said his top priority was to protect the interests of the Iraqi people under the U.S.-led occupation.
Deputy Syrian ambassador Fayssal Mekdad, whose country holds the Security Council presidency, said "such terrorist incidents cannot break the will of the international community" and that U.N. programs would continue.
In other developments in Iraq: