The soldiers were the first casualties suffered by the Army's 1st Infantry Division's 1st Battalion, 18th Infantry Regiment, which is taking over security in the Tikrit area as part of the military's massive troops rotation in Iraq.

 

They were killed by a roadside bomb that destroyed their armored Humvee around dawn, hours before a handover ceremony Saturday. Four other soldiers were wounded, said Capt. Tim Crowe.

After the attack, about 50 soldiers fanned out through the city searching for evidence and asking locals for information about the attack. Around 700 troops from the 18th Regiment are replacing the same number from the st Battalion 22nd Infantry Regiment patrolling Tikrit, Saddam Hussein's hometown and a center for insurgent activity north of Baghdad.

Roadside bombs have become the main threat to U.S. soldiers on patrol in the Sunni Triangle, a region has seen some of the fiercest guerrilla fighting. Three U.S. soldiers were killed and three wounded Thursday by bombs near the towns of Habbaniyah and Baqouba.

The apparent role of Iraqi policemen in Tuesday's slayings of two U.S. coalition officers and an Iraqi woman working as their translator south of Baghdad raised concerns that insurgents are infiltrating the security forces being trained by U.S. forces.

U.S. troops have been setting up Iraqi police and other security forces, intending to gradually put them on the frontlines against guerrillas.

Four Iraqis with active police identification were caught along with a former officer from the Saddam-era police forces and a civilian after the slayings, Maj. Gen. Mark Kimmitt said.

Coalition spokesman Dan Senor called the policemen's role in the attack "an exception" and defended what he called a "robust" process of vetting police recruits to try to uncover criminal pasts or links to Saddam's regime. "But it is not perfect," he said. "Individuals slip through the cracks. We act to identify it and remove them immediately."

FBI experts were investigating the attack that killed the three, amid conflicting reports over the shooting outside the town of Hillah. Polish troops patrolling the region said the police stopped the victims' car at a checkpoint and shot them to death.

Kimmitt, however, said the attackers may have been in a second car that ran the coalition staffers off the road.

Coalition spokesman Dan Senor called the policemen's role in the attack "an exception" and defended what he called a "robust" process of vetting police recruits to try to uncover criminal pasts or links to Saddam's regime. "But it is not perfect," he said. "Individuals slip through the cracks. We act to identify it and remove them immediately."

The American civilians were the first from the U.S. occupation authority to be killed in Iraq. One was Fern Holland, 33, a human rights expert from Oklahoma who worked on women's issues in the Hillah region. The other was a regional press officer, Robert J. Zangas, 44, of suburban Pittsburgh.

Kimmitt said four of the six men in custody, caught together in the same car soon after the attack, had current police identification. Investigators were examining whether they were authentic but "we believe they are valid," he said.

U.S. officials have trained more than 70,000 Iraqi police officers, as well as some 25,000 members of the Iraqi Civil Defense Corps, or ICDC, in a matter of months. New recruits undergo an eight-week training program, while veteran officers have three weeks of training on new techniques and democratic principles, Senor said.

Recruits are vetted, but records for criminal activity or past links to Saddam's regime are scattered and difficult to track down.

On Monday, U.S. troops arrested one current and two former ICDC soldiers for selling weapons to insurgents and carrying out bomb attacks on the homes of Iraqis cooperating with American forces in Tikrit.

Lt. Col. Steve Russell, a battalion commander in Tikrit, said infiltration is "not a major problem."

"In terms of the ICDC, this is where those that were not properly scrutinized may sometimes have their loyalties elsewhere. But these represent a very small number," he said.

Russell said information provided by ICDC officers led to the arrests, "proving that they don't want a negative reputation" for their forces.

As part of the recruiting process in Tikrit, Russell said he has local tribal leaders vouch for those wanting to join and those who don't get the sheik's nod are turned down. The three ICDC members caught Monday were trained outside the area and would not have gone through that process, he said.

AP correspondent Lee Keath contributed to this report from Baghdad

photo credit and caption:

An armed security guard watches as an elderly Iraqi Shiite is helped to go to the Kazimiya Shrine to attend the regular Friday prayers, in Baghdad, Iraq, Friday March 12, 2004. Security has been tightened around the Shrine following coordinated attacks ten days ago, the bloodiest in Iraq since the fall of Saddam Hussein. The coordinated attacks at the Shrines in Baghdad and in Karbala killed 181 people and injured 573 others. (AP Photo/Murad Sezer)