According to US officials, resistance fighters fired three RPGs into a Fallujah police station in another day of sporadic attacks on the occupiers.
"Three soldiers were hit, and three policemen were injured," police officer Mohammed Abd Al-Zaki, who was in the station when it was attacked, said.
"Two Americans are probably dead, with one injured."
A US military spokeswoman later confirmed one Third Armoured Cavalry Regiment soldier was wounded in Tuesday's attack.
After the attack a correspondent with the AFP news agency saw US troops quickly leaving the station in military vehicles. They were seen shooting as they left.
A fourth Iraqi, a 15-year-old child, was injured by gunfire as the US soldier convoy departed.
The Americans took their injured to the Jordanian Hospital in Fallujah, while Iraqi policemen took their wounded and the child to another hospital.
Following the attack, some 200 people gathered near the station to stage a protest, chanting: "With our blood and with our soul, we will defend you, Saddam!"
Fallujah is one of several towns in a so-called Sunni triangle west and north of Baghdad known to harbour strong support for ousted Iraqi leader Saddam Hussein.
US civilian dead
Meanwhile a US civilian contractor was killed while a trio of Iraqi policemen were wounded in a separate attacks.
The employee of Kellogg, Brown and Root (KBR), contracted by the US army to help rebuild Iraq’s oil infrastructure, was killed when his vehicle ran over an explosive device near Tikrit.
US soldiers have come under daily
attacks since 1 May
KBR identified the man as an employee but said the blast was caused by an anti-tank mine.
He was believed to be the first US civilian fatality here since US President George W. Bush declared an end to major combat in Iraq on 1 May.
It was not clear if the contractor, driving in a five-man convoy, was targeted by assailants or if he hit the explosive by accident.
In Tikrit, three rounds of mortar fire landed in a lake in a former presidential compound without causing any casualties or damage, said Captain Allen Hansen.
"I was in the bathroom and three mortars landed in the lake. It was a loud explosion and the glass shook," he said.
A US army spokesman in the Tikrit region, Lieutenant Colonel Bill MacDonald said the presidential compound is often targeted by mortar or rocket fire, but without causing any harm to date.