Iraqi officials say gunmen have ambushed a bus of workers heading to Baghdad's international airport.

Reports initially said nine people were killed in the attack Monday, but Iraqi sources are now quoted saying four people died.

Officials say most of the passengers were Shi'ites. The bus was passing through a Sunni district of western Baghdad at the time of the attack.

In other violence in Baghdad, at least five members of a Shi'ite family were gunned down in the Dora neighborhood, while a roadside bomb killed two people in the Zafaraniya district.

And north of the capital, near the city of Samarra, gunmen kidnapped a tribal council chief.

Iraqi authorities say security forces killed some two dozen suspected militants in a series of raids in Baghdad since Sunday. The U.S. military today also reported the combat deaths of two American soldiers Sunday.

Separately, the United Nations refugee agency today made an emergency appeal for $60 million to help Iraqi refugees. The agency says some one-point-seven million Iraqis are internally displaced, while as many as two million others have fled the country.

The U.N. agency says up to 50,000 Iraqis flee their homes every month.

In other news, a former Iraqi official who escaped from jail in the heavily fortified Green Zone said he hopes to soon return to the United States.

Ayham al-Sammarai, who holds dual Iraqi and American citizenship, was jailed for corruption. Speaking at a news conference in Dubai, Sammarai alleged that the charges against him were political, and that he feared he would be kidnapped or killed once he was released.

Some information for this report was provided by AFP, AP and Reuters.