Hopes of finding survivors faded Wednesday afternoon, 24 hours after an explosives-rigged truck brought down the facade of U.N. offices in the Canal Hotel, killing at least 20 people including the top U.N. envoy in Iraq, Sergio Vieira de Mello. About 100 people were wounded.
A key member of the U.S.-picked interim government said the death toll could go much higher. About 300 U.N. employees worked at the headquarters.
"There are many who are still trapped in there," said Ahmad Chalabi, a member of the Governing Council and leader of the Iraqi National Congress.
In other developments:
Unlike U.S. occupation forces, the United Nations had been welcomed by many Iraqis. But U.S. officials say Tuesday's attack fits the terrorist strategy of trying to block aid and anger the population to turn it against American occupiers.
An FBI team that was already in Baghdad investigating the car bombing of the Jordanian Embassy two weeks ago, in which 19 died, has now been assigned to the Canal Hotel attack.
FBI Special Agent Thomas Fuentes said the bomb had been delivered by a KAMAZ flatbed truck. Such trucks were made in the former Soviet Union. U.S. officials had said on Tuesday that a cement truck delivered the explosives.
Fuentes said human remains found in the area where the bomb exploded, about 50 feet from Vieira de Mello's office, suggested a suicide bombing. He said that could not be absolutely determined until laboratory testing was complete.
The cement truck detonated at the concrete wall outside the three-story Canal Hotel at 4:30 p.m. Tuesday, blasting a 6-foot-deep crater in the ground, shredding the facade of the hotel housing U.N. offices.
Chalabi also said the Governing Council had received information Aug. 14 — just days before the bombing — that there would be a terror attack in Baghdad, and that the council warned the United States.
But except for the recently built concrete wall, U.N. officials at the headquarters refused heavy security because the United Nations "did not want a large American presence outside," said Salim Lone, the U.N. spokesman in Baghdad.
Fifteen bodies in white bags were counted by a U.N. worker at the hotel, and a survey of Baghdad hospitals by The Associated Press found five other people killed in the blast. Veronique Taveau, a spokeswoman for the U.N. Humanitarian Coordinator, said the U.N. figure for the dead was 17 and 100 people were wounded.
"There are so many people who are still missing," she said.
One of the victims was an American — Richard Hooper, 40, was an Arab expert from California on special assignment with the U.N.
Vieira de Mello, a 55-year-old veteran diplomat from Brazil, was wounded and trapped in the rubble, and workers gave him water as they tried to extricate him. Hours later, the United Nations announced his death.
Taveau said U.N. operations in Iraq were suspended and travel arrangements were being made for employees who wanted to leave. Local employees were told to stay home. Foreign workers were directed to stay in small hotels around the capital.
CBS News Correspondent Kimberly Dozier reports the U.S. Military has tightened security around the city, parking three Bradley armored fighting vehicles at one U.N. facility. The British Embassy was closed because of a bomb threat.
The U.N. Staff Council's security committee called on Annan "to suspend all operations in Iraq and withdraw its staff until such time as measures can be taken to improve security."
But both the Security Council and Annan said in statements that the United Nations would be undeterred by the violence.
"We will persevere. We will continue. It is essential work," he said at a news conference in Stockholm, Sweden, where he stopped briefly before heading to U.N. headquarters in New York. "We will not be intimidated."
Annan also told reporters that "some wrong assumptions may have been made" about stabilizing the nation.
L. Paul Bremer, the top civilian administrator, denied the attack demonstrated a loss of control by American forces.
"We have a security problem here. The security problem now has got a terrorist dimension, which is new. But the rest of the security is basically in better shape than it was three months ago when I arrived here," Bremer told the CBS News Early Show.