Up to four Iraqi civilians are reported to have died in Baghdad when US troops fired at a minibus taking them to work.
Baghdad says it will extend US troops' stay beyond 2008
The US military in Iraq said its forces opened fire at the vehicle "after the driver failed to heed a warning shot".
A US military statement said the road the minibus was travelling on, in the Shaab area of north-east Baghdad, was only for use by passenger cars.
Iraq police and medics said three women and a man had died; the military said it knew of two dead and two wounded.
Police sources said the bus was carrying Finance Ministry employees to work.
The US military has also given details of an incident that happened on Monday when three Iraqi civilians, including a child, were killed by its troops manning a roadblock 200 kilometres (140 miles) north of Baghdad. It said their vehicle approached the roadblock in the city of Baiji at high speed and the driver ignored warnings to stop.
The deaths come a day after the Baghdad government said it would seek a renewal of the UN mandate to keep US-led forces in Iraq until the end of 2008, after which it wanted a bilateral pact with the US.
Correspondents say the US military presence is unpopular among many of the Iraqi population, because of what is seen as the heavy-handed use of force by US troops.
Separately, a suicide bomber killed three policemen in an attack on the Diyala provincial police headquarters in Baquba, 65 km (40 miles) north of Baghdad, police said.
Three civilians, including two women, were also killed during the incident. Reuters news agency said they died in gunfire after the blast.