"This could have been any enemy that saw a soft target and saw the opportunity to shoot either at a coalition vehicle, a private vehicle, or a military vehicle," said Kimmitt, the coalition deputy director.
At the scene early Sunday, angry young men who called themselves "moujahedeen" -- or holy warriors -- applauded the attack on the Spanish and vowed that such strikes would mount. Several said they had been involved in the attack and one, who gave his name as Muhannad Janabi, displayed a passport he said was taken from one of the dead Spaniards.
"Everyone here will fight the Americans and their allies," said Janabi, who described himself as a 31-year-old farmer in the broad plain between the Tigris and Euphrates south of the capital. "We are fighting in the path of God. No one can defeat us. We are willing to give our lives to this fight against the invaders."
The two vehicles were targeted because they appeared to be ferrying foreigners, Janabi said.
One or two cars followed the Spaniards' vehicles before pulling alongside them and opening fire, according to official accounts. The Spaniards' two vehicles were forced to the side of the road on the outskirts Latifiyah, a town where the pro-U.S. police chief and a prominent contractor had been assassinated a week earlier.
On the side of the road, other attackers positioned nearby opened fire, the Army said. It is unclear whether the Spanish agents, who were armed, had the opportunity to fire back.
A crowd of more than 100 people -- some armed with sticks and clubs -- soon descended on the scene and looted bodies and the vehicles, both of which burned, said Johnson of the 82nd Airborne. Television footage shot by a passing news crew showed a handful of joyous Iraqis celebrating amid the carnage.
But one Spanish agent was somehow able to evade the attackers and escape by flagging a passing police car, the Army said.
It took the Army about one hour and 20 minutes to reach the scene of the ambush. Contributing factors, Johnson said, were a delay in reporting the incident to police and traffic en route to the site.
Spain has been a strong supporter of the U.S.-led invasion of Iraq and has sent about 1,300 troops here. Sunday's deaths were not its first losses from hostile fire. A Spanish diplomat working with Spain's intelligence agency was assassinated in Baghdad in October, and a Spanish navy captain was killed in the truck bombing of the United Nations headquarters in Baghdad in August.
The news of the slayings Saturday hit the Spanish contingent here hard. The principal job of the agents was to provide security and guidance to the Spanish troops deployed in Iraq, said Maj. Jose Luis Perez Ucha at the Spanish garrison in Najaf. He said he had known two of the agents, former military men, for more than 20 years.
"I am in complete shock that this has happened -- I am floating I am so sad," Perez said. "These were fine men. They were not involved in espionage. They were like us: Just trying to help the people of Iraq. This is a great tragedy."
Daniszewski reported from Samarra and McDonnell from Baghdad. Times staff writers Edmund Sanders in Washington and Barbara Demick in Seoul contributed to this report.