Scores also were wounded in clashes in the town near the Iraq-Syria border, an eyewitness told Aljazeera.
Hassan Jasim, who spoke to Aljazeera from al-Qaim, said US forces made announcements through loudspeakers instructing people to leave the city because warplanes would launch heavy air strikes on the positions of the armed men.
Jasim, a resident of al-Qaim, said, "US troops have launched a savage attack against the city and a large number of people have been killed and injured."
"The bombing started half an hour ago," he added.
He said water and electricity were cut because of the air strike.
"The streets are filled with dead and injured people and no one could reach or help them due to the fighting," he said.
Earlier this year US forces hit the same desert region with heavy artillery, destroying parts of the city. The military then said it was targeting "foreign fighters" in the area who slip through the border.
US forces launched Operation
Matador in May
Iraqis in al-Qaim, however, said there are no foreigners among them.
The offensive, code-named Operation Matador, was described as one of the largest by the US military in Iraq in six months.
Meanwhile, in a separate incident, a group calling itself the Islamic Army in Iraq has claimed responsibility for a roadside bomb attack against a US military vehicle along the main road near the city of Ramadi in western Iraq in a videotape posted on an internet website.
The authenticity of the video could not be verified by an independent source.