U.S. and Iraqi officials Wednesday were investigating yet another shooting of Iraqi civilians by a heavily armed security firm linked to U.S. government-financed work in Iraq.

The bodies of Marou Awanis and Geneva Jalal, the Christian women killed in the Tuesday shooting, were taken, meanwhile, to Baghdad's Armenian Orthodox Virgin Mary Church for funeral services.

Iraqi authorities blamed the women's deaths on guards working for Unity Resources Group, a security company owned by Australian partners but with headquarters in Dubai in the United Arab Emirates.

Unity provides security services to RTI International, a group based in Research Triangle Park, N.C., that promotes governance projects in Iraq for the U.S. Agency for International Development.

Both Unity and RTI acknowledged a security contract between them and both entities said RTI staffers were not present when the shooting occurred in Baghdad's Karradah district.

A U.S. Embassy spokeswoman said RTI was under contract by USAID but was responsible for its own security.

"USAID does not direct the security arrangements of contractors," Mirembe Nantongo said.

According to the USAID Web site, RTI has about $450 million in U.S. government contracts to work on local governance projects in Iraq. USAID is a semi-autonomous arm of the U.S. State Department that manages American aide programs.

Michael Priddin, chief operating officer of Unity, told The Associated Press on Wednesday the firm was working with Iraqi authorities "to find out the results of the shooting incident. ...we are trying to work out a true picture of what happened."

In a statement issued Tuesday night, Priddin said, "We deeply regret this incident."

Iraqi government officials, police and witnesses said guards working for Unity fired on a white Oldsmobile as it approached their convoy Tuesday afternoon, killing the two women before speeding away from the latest bloodshed blamed on the deadly mix of heavily armed protection details on Baghdad's crowded streets.

The deaths of the women — including one who used the white sedan as an unofficial taxi to raise money for her family — came a day after the Iraqi government handed U.S. officials a report demanding hefty payments and the ouster from Iraq of embattled Blackwater USA for a chaotic shooting last month that left at least 17 civilians dead.

The Tuesday killings were certain to sharpen Iraqi government demands to curb the expanding array of security firms in Iraq watching over diplomats, aid groups and others.

Accounts of the incident — from company statements, witnesses and others — suggested the Unity guards opened fire as the car failed to heed warnings to stop and drifted closer to the convoy near a Unity facility in Karrahah.

Statements from both Unity and RTI have made clear the guards were not escorting RTI clients when the shooting occurred.

Four armored SUVs — three white and one gray — were about 100 yards from a main intersection in the Shiite-controlled district at about 1:40 p.m. As the car moved into the crossroads, the Unity guards threw a smoke bomb in an apparent bid to warn the driver not to come closer, said Riyadh Majid, an Iraqi policeman who saw the shooting.

Two of the Unity guards then opened fire. The woman driving the car tried to stop, but was killed along with her passenger. Two of three people in the back seat were wounded.

Priddin's Tuesday statement offered a similar account: "The first information that we have is that our security team was approached at speed by a vehicle which failed to stop despite an escalation of warnings which included hand signals and a signal flare. Finally shots were fired at the vehicle and it stopped."

Iraqi police investigators said they collected 19 spent 5.56 mm shell casings, ammunition commonly used by U.S. and NATO forces and most Western security organizations. The pavement was stained with blood and covered with shattered glass from the car windows.

Majid said the convoy raced away after the shooting. Iraqi police came to collect the bodies and tow the car to the local station.

A second policeman, who spoke on condition of anonymity because he feared retribution, said the guards were masked and wearing khaki uniforms. He said one of them left the vehicle and started to shoot at the car while another opened fire from the open back door of a separate SUV.

Marou Awanis was born in 1959, Geneva Jalal in 1977. Awanis' sister-in-law, Anahet Bougous, said the woman had been using her car to drive government employees to work to help raise money for her three daughters. Her husband died during heart surgery last year.

"May God take revenge on those killers," Bougous said, crying outside the police station. "Now, who is going to raise them?"

"These are innocent people killed by people who have no heart or consciousness. The Iraqi people have no value to them," said a man who was part of a group of relatives gathered with a Christian priest at the local police station.

Iraqi anger has grown against the private security companies — nearly all based in the United States, Britian and other Western countries — as symbols of the lawlessness that has ravaged their country for more than four years.

Ali al-Dabbagh, Iraq's government spokesman, said: "Today's incident is part of a series of reckless actions by some security companies."

An Iraqi investigation of the Blackwater shooting on Sept. 16 was ordered by Prime Minister Nouri al-Maliki and called for the company to pay $8 million in compensation to the families of each of the 17 victims. The commission also said Blackwater guards had killed 21 other Iraqis in past incidents since it began protecting American diplomats in Iraq shortly after the U.S.-led invasion in 2003.

Unity also has come under scrutiny before.

In March 2006, the company issued an statement of sympathy after one of its guards was blamed for shooting a 72-year-old Iraqi-born Australian, Kays Juma, at a security checkpoint in Baghdad.

Australian Foreign Minister Alexander Downer said Juma was killed because he was in a car that failed to stop. Unity said multi-national forces and Iraqi police also were present at the checkpoint at the time.

Unity provides armed guards and security training throughout Iraq. Its heavily armed teams are Special Forces veterans from Australia, the United States, New Zealand and Britain — as well as former law enforcement officers from those countries.