The Bush administration is concerned that Iraqi police do not possess the abilities, such as bomb blast analysis, to properly investigate deadly attack, said a senior Justice Department official, speaking on condition of anonymity from Washington.
The FBI team, of fewer than a dozen, will mainly secure and analyze evidence at the bombing site and likely help train Iraqi investigators in the same skills, the official said. It was not immediately clear precisely when the team would arrive or how long it would stay.
In Saddam Hussein's hometown of Tikrit, meanwhile, U.S. snipers firing from 100 yards away killed two suspected arms dealers in a market. The Iraqis were given no opportunity to surrender; an Army colonel said their weapons made them combatants.
The military also said a U.S. soldier was killed Thursday night in Baghdad while on guard duty. It was not clear, the Army said, if the soldier was attacked or shot accidentally.
In the investigation of Thursday's embassy bombing, authorities are looking at Ansar al-Islam, an al Qaeda-linked group, as a potential suspect, Lt. Gen. Norton Schwartz, director of operations for the Joint Chiefs of Staff, told U.S.-run Radio Sawa. The station broadcasts to the Middle East in Arabic.
"The one organization that we have confidence and that we know is in Iraq and in the Baghdad area is Ansar al-Islam," he said. "It is unknown whether this particular organization was associated with the (bombing). Perhaps that'll become clear as we go down the road.
"But that is an al Qaeda-related organization and one that we are focusing attention on," Schwartz said.
The bombing was the first large-scale terrorist attack since Baghdad fell to U.S. forces April 9 and it made Thursday the bloodiest since President Bush declared an end to major combat.
Before the U.S. invasion of Iraq, Ansar al-Islam was known for bombings and assassinations of Kurdish figures. But the group, which has included veterans of bin Laden's training camps in Afghanistan, has not previously been linked to attacks on the scale of the embassy blast.
Secretary of State Colin Powell said the group was a link between Baghdad and al Qaeda when he made his case for war to the U.N. Security Council in February. Others have questioned whether there was any connection to Saddam's regime.
U.S. forces knocked out Ansar-al-Islam's main headquarters in northeastern Iraq early in the war. L. Paul Bremer, the U.S. administrator of Iraq, has said the group has been rebuilding in the country, with surviving members filtering back from Iran.
More than 50 people were wounded in the explosion at the embassy, which set cars on fire, flung the hulk of one vehicle onto a rooftop and broke windows hundreds of yards away.
On Friday, the Jordanian flag flew at half-staff. Two Humvees kept the area sealed off. Sgt. 1st Class Chris Lynch of the 82nd Airborne Division said the Iraqis and Americans were cooperating in the investigation.
So far, American authorities have said, they do not believe terrorist groups like Ansar or any other foreign fighters have played a major role in the guerrilla war against American occupation forces.
They believe instead that the attacks are the work of remnants of Saddam's regime — his Republican Guard, Fedayeen militia and intelligence services.
"What this shows is that in fact we have some terrorists that are operating here," said Lt. Gen. Ricardo Sanchez, commander of U.S.-led forces in Iraq. "It shows we are still in a conflict zone."
The military reported Friday that a U.S. soldier died from a gunshot in Baghdad the night before. Authorities said they had not determined if he was killed in an attack or died in an accidental shooting. Two soldiers died Wednesday night in an attack in Baghdad, the first such deaths since Aug. 1.
Also Friday, U.S. snipers killed two men and wounded two others in a raid on the weapons market in Tikrit, witnesses and military officials said.
Women ran screaming as they heard the shots and saw a man, who was unloading AK-47 assault rifles from the trunk of a red sedan, fall to the ground, said a witness who was selling biscuits.
U.S. forces had positioned snipers around the market after hearing that weapons and ammunition were sold there every Friday, said Lt. Col. Steve Russell, whose 22nd Infantry Regiment, 1st Battalion, carried out the operation.
"We didn't give them a chance to engage us. If you walk around with weapons in a city, you become a combatant. The rules are very clear," he said.
Dr. Mohammed al-Jubori said three people were killed. He said two died in the market and a third, shot in the head, died at a hospital. He said five were wounded, including a 10-year-old boy.
Hundreds of residents watched from across the road as soldiers examined the scene and Iraqi police removed a body covered in a black-and-white headscarf. Soldiers said that victim was shot as he tried to flee with an AK-47.
Next to the red car, the earth was soaked with blood at the spot where Russell said one of the alleged arms dealers was shot as he unloaded rifles. Soldiers showed reporters an ID card bearing the dead man's photo that had been issued by Saddam's regime.