Six U.S. Marines were injured and their Iraqi interpreter was killed Friday when a roadside bomb struck their patrol near Fallouja, the military said.
There was at least one other explosion in the city during the day, underscoring fears that Sunni Arab militants loyal to Al Qaeda in Iraq may be attempting to stage a comeback in their former stronghold.
The U.S. military also announced the death of a soldier Thursday in a roadside bombing about 12 miles southwest of Baghdad. At least 4,080 American military personnel have died since U.S.-led forces invaded Iraq in March 2003, according to icasualties.org.
The city of Fallouja, the scene of a major showdown between insurgents and U.S. forces in 2004, has seen a marked decline in violence since Sunni tribesmen in Anbar province rebelled against militants in 2006. The uprising was the model for the U.S. military's Sons of Iraq program, which has hired more than 90,000 tribesmen, mostly Sunnis, nationwide to help defend their areas against extremists.
However, the province recently has been hit by a string of bombings targeting U.S. and Iraqi security forces and their tribal allies.
A U.S. military statement said the Marines were attacked by unknown assailants northwest of the city.
In a separate incident Friday, Fallouja police chief Col. Faisal Ismail Hussein said an explosives-laden car detonated as officers took the vehicle inside their compound to be defused, injuring four officers.
The U.S. military said one police officer was killed and none injured in the incident. The reason for the discrepancy was not immediately clear.
Police found another vehicle rigged to explode and detained its three occupants, Hussein said. That vehicle contained seven bombs, he said.
In the southern city of Basra, representatives of radical Shiite Muslim cleric Muqtada Sadr said one person was killed and two injured when Iraqi security forces fired in the air to prevent the cleric's followers from gathering in a square for midday prayers.
Hospital officials confirmed the two wounded but said they did not receive a corpse. Iraqi police and military officials said they had no information on the matter.
In Balad, the U.S. military said more than 140 suspected insurgents turned themselves in Thursday after three tribal leaders ended a violent standoff with U.S. and Iraqi forces in the city, 50 miles north of Baghdad. The mass surrender came after three other leaders were killed in recent operations, the military said.
Police in the northern town of Hawija said a bomb exploded Friday amid a crowd, killing one person and injuring three.
Special correspondents in Baghdad, Fallouja and Kirkuk contributed to this report.