According to Aljazeera's correspondent, the attack took place near the public hospital in Ramadi city on Tuesday. No further details are yet available.
This attack follows three separate incidents on Monday, in which three US soldiers were killed.
Late on Monday night, a roadside bomb killed one US soldier and wounded another in northern Iraq.
According to the US military, the soldiers were travelling in a convoy near Tall Afar, about 400km northwest of Baghdad, when the bomb exploded.
One soldier died while being taken to a nearby hospital by helicopter, the military said.
Soldiers in the convoy fired on several attackers after the explosion, but were unable to capture anyone, the military said.
The latest death brings to about 376 the number of US soldiers killed in action in Iraq since the US-led invasion last March which toppled Saddam Hussein.
Earlier on Monday, two US soldiers died in separate attacks on convoys in central and north Baghdad.
Video store bombed
Also on Tuesday a bomb has exploded at a video store in the southern Iraqi town of Samawa where Japanese and Dutch
troops are based, and police said the shop was apparently targeted because of rumours that it sold pornographic DVDs and compact discs.
Japanese troops are based in
the town of Samawa
No one was injured in the blast - the second targeting a video shop in the town since 22 January.
The pre-dawn explosion caused only minor damage, Iraqi Police Sergeant Hasan Tuhayir said.
The owner, 17-year-old Mustafa Halim, said he only sold religious compact discs, adding "I have no enemies."
The explosion, which was caused by TNT, left a small hole outside the shop, broke nearby windows and knocked dozens of CDs off the shelves.
Tuhayir said the blast, like the last one, might have been set off by Iraqis angered by the presence of pornographic products.
A small advance team of about 30 Japanese soldiers are preparing a camp for an expected 600 troops by March to live and work there.
Until the main units are settled in, the Japanese soldiers are staying with Dutch forces in Camp Smitty while they prepare their own camp about 6km out of town.