BAGHDAD, Iraq (CNN) -- The U.S. Army has ordered an investigation into the deaths of an Iraqi family of four at their home in Mahmoudiya, a town south of Baghdad, a U.S. military statement said Friday.

The investigation concerns allegations that at least two U.S. soldiers were involved in the rape of a woman and that one of them killed her, a child and two other adults, U.S. military sources said.

Maj. Gen. James D. Thurman, commanding general of Multinational Division-Baghdad, ordered the Army's Criminal Investigation Command to conduct the investigation.

"A preliminary inquiry conducted by MND Baghdad found sufficient information existed to recommend a criminal investigation into the incident," the statement said.

The allegations came to light on June 23, when a soldier undergoing a stress debriefing said he heard that other soldiers might have been involved in a rape and murder in March.

That soldier is from the 502nd Infantry Regiment of the 101st Airborne Division, the same unit as the three soldiers involved in the checkpoint attack June 16 near Yusifiya. In that incident, Spc. David J. Babineau was killed, and two others -- Army Pfc. Kristian Menchaca and Pfc. Thomas Tucker -- were abducted and later found dead.

Soldiers in the unit were given stress counseling afterward.

The military said it interviewed a second soldier, who gave a report similar to the first. That soldier said he saw bloodstains on other soldiers' clothing and heard them conspire to commit such an act.

Both soldiers said they didn't witness the alleged incident.

The investigation into the deaths began Saturday.

It is among a number of investigations into alleged killings of civilians by U.S. forces in Iraq. Four Army soldiers have been charged with murder in the deaths of three Iraqi detainees during an operation in Salaheddin province in May. Seven Marines and a sailor also have been charged with murder for the death of an Iraqi civilian in Hamdaniya in April.

In a case that has yielded no charges, the military is investigating allegations that up to eight Marines killed as many as 24 Iraqi civilians in Haditha in November.

Child victims

Children were among the victims of deadly violence Friday in Iraq, emergency police told CNN.

A firefight between gunmen and Iraqi soldiers Friday morning left a teenage girl dead in the Babil province town of Latifiya, about 20 miles south of Baghdad.

Also, one of six bodies found Friday in Baghdad was that of a boy believed to be between 4 and 6 years old. He was shot, and his body showed signs of torture.

The dumping of bodies across the capital has been a common occurrence since sectarian violence escalated after the bombing on February 22 of the Askariya Mosque, a Shiite shrine, in Samarra.

U.S. troops killed

Also Friday, the U.S. military announced four troop deaths.

A bombing Thursday night killed a Multinational Division-Baghdad soldier on foot patrol south of the capital.

In a separate incident Thursday night, a bomb killed a soldier and wounded another while they were on patrol near Balad, a military statement said. They were assigned to the 1st Brigade, 34th Infantry Division Brigade Combat Team.

Small arms fire killed a third U.S. soldier in the northern Iraqi city of Mosul on Thursday, the military said. That soldier served with Task Force Band of Brothers -- the 172nd Stryker Brigade Combat Team.

A Marine assigned to Regimental Combat Team 5 died Wednesday from wounds "due to enemy action" in Anbar province, west of Baghdad, another military statement said.

Since the start of the war, 2,525 U.S. military personnel have been killed in Iraq. Seven American civilian contractors of the Pentagon have also been killed.

Other developments

• Gunmen west of Kirkuk attacked an Iraqi military checkpoint Friday afternoon, killing the five soldiers there, police told CNN. The attack came a day after a suicide car bombing that targeted a wake for an Iraqi soldier killed five people and wounded more than 30.
  
  
• A CIA analysis has concluded that the voice on an audiotape released on an al Qaeda Web site Thursday night is that of Osama bin Laden, a CIA representative said. The message mourned the death of al Qaeda in Iraq leader Abu Musab al-Zarqawi.
  
  
• Russia is posting a $10 million reward for information on the killers of five Russian diplomats, four of whom were slain after being abducted in Iraq earlier this month, the Interfax news agency reported Friday.
  
  
• The baby who was brought to the United States for lifesaving medical treatment is back home in Iraq. U.S. soldiers last year discovered Baby Noor, who was born with the crippling defect spina bifida.
  
  
• Iraqi Prime Minister Nuri al-Maliki on Saturday will embark on a five-day trip, his colleague and Shiite parliamentarian Hasan al-Seneid told CNN. Al-Maliki will stop in Kuwait, Saudi Arabia and the United Arab Emirates, where he'll discuss bilateral relations, Iraq's national reconciliation plan and political process, and border and security issues.
  
  
• Romania will not withdraw its troops from Iraq, President Traian Basescu said Friday, reversing an order made by the country's prime minister the day before. Basescu added, however, that the country will seek a reduction of its troops there.

CNN's Barbara Starr, Arwa Damon, Jomana Karadsheh and Pam Benson contributed to this report.

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