There has been an attack on a US army convoy in Iraq, near to the scene of a major American offensive against armed supporters of Saddam Hussein.
The troops were vulnerable in the back of an open lorry
A number of US soldiers are reported to have been wounded. It is not yet known how many were injured, and whether there were any fatalities.
The attack took place 70 kilometres (40 miles) out of Baghdad on the main road north.
It left a lorry that had been carrying troops a burnt-out wreck, while television pictures showed another vehicle - possibly a trailer - also on fire.
The BBC's Jim Muir, in Baghdad, says the attackers apparently caught the convoy unawares, with soldiers being carried unprotected and vulnerable in the back of an open truck.
It was the latest in a series of attacks on US forces in Iraq
He adds that it is a considerable embarrassment for the Americans, coming soon after the end of a much publicised offensive in the riverside country around the nearby town of Balad.
Thousands of US troops took part in the operation around Balad, part of a series of raids codenamed Peninsula Strike.
It was launched after a series of attacks on US forces in the area.
Our correspondent says the fact that the Americans should then take another hit so soon and so close by is a clear sign that the coalition's enemies are determined not to be intimidated by such shows of force.
It also shows just how vulnerable the American troops may be to the kind of hit-and-run guerrilla tactics that this attack exemplified.
In other developments:
- Hundreds of people in city of Basra demonstrate in support of demands that the British Army should allow Iraqis to run Iraq's southern capital
- The US military announces that the former commander of the Iraqi air force, Hamid Raja Shalah al-Tikriti, is now in US custody
The chairman of the US Joint Chiefs of Staff, General Richard Myers, says Saddam
Hussein is probably alive and is being sought by US forces.
The latest attack by Iraqi militiamen came after US forces took part in another operation, Desert Scorpion, on Sunday.
About 1,300 soldiers from the 3rd Infantry Division backed by tanks and helicopters raided the town of Falluja, west of Baghdad.
The area was a stronghold of former President Saddam Hussein and is regarded as a focal point of Iraqi resistance.
Falluja has seen many clashes between US troops and Iraqis
The troops were acting on intelligence that Iraqi militia fighters were based in the town and that weapons were being stockpiled there for use against US forces.
They withdrew after three hours, having made seven arrests.
US troops returned later with medical and school supplies, as well as toys, in an effort to win over the local population which has complained of heavy-handedness by the troops.
But the mayor of the town told the BBC the raid had been carried out quietly, and that he believed the US forces in the area were starting to behave in a more sensitive manner.