Hospital officials and witnesses said the dead were civilians. Witnesses said the strike hit the main road leading out of the north of the city.
The US military said marine jets had launched a "precision" strike that destroyed a "rebel site".
US warplanes have been bombing the city almost daily in what they say is a bid to crush armed fighters and kill or capture al-Qaida-linked Abu Musab al-Zarqawi and his followers.
Falluja residents deny any knowledge of al-Zarqawi and say the raids have inflicted heavy civilian casualties.
In Samarra, a 17-year-old girl and an 11-year-old Iraqi boy were killed and four people wounded in clashes between US troops and fighters, police said on Sunday.
Samarra residents say US forces
and armed fighters skirmish daily
Police said the two were killed on the northern outskirts of the city 100km from the Iraqi capital, in the fighting on Saturday evening.
Witnesses said a US military Humvee vehicle was also damaged.
A US military spokeswoman had no immediate comment.
US troops and Iraqi National Guards have maintained a strong presence in most parts of the mainly Sunni Muslim city since an assault early this month that resulted in the deaths and detention of several fighters.
The Iraqi government said Samarra had been pacified in that assault, part of a plan to retake all "rebel" areas by political or military means before elections planned for January.
But residents say US troops and fighters skirmish daily in the city, which remains under curfew at night.
US officer killed
In Baghdad a US state department security officer was killed on Sunday during a mortar or rocket attack at a US base near Baghdad International Airport, the US embassy announced.
Ed Seitz, an agent with the state department's bureau of diplomatic security, was killed at about 5am (0200 GMT) at Camp Victory, embassy spokesman Bob Callahan said. Camp Victory is the headquarters of the US-led command's ground forces command.
An undetermined number of people were hurt in the attack but none with life-threatening injuries, Callahan said.
Aljazeera has also learned that a car bomb exploded near a US patrol near a governmental compound in the Abu Ghraib area of Baghdad.
The explosion has caused casualties among the soldiers and damaged some vehicles. No further details were available.
Elsewhere, an explosive device detonated on the Kharnabat bridge in western Baghdad, destroying a tank that later fell into the Tigris river. US forces sealed off the site.