At least eight Iraqis, mostly women and children, were killed in a double car bombing in Samarra on Wednesday, Iraqi medical and security officials say.
The Samarra bombs were exploded near a US convoy
The two suicide attackers reportedly exploded the bombs in the path of a US army convoy near a nursery school.
The US military said 11 soldiers were wounded in the blasts.
It was the first major attack since control of the city was seized from insurgents by US and Iraqi interim government forces early in October.
It said on Wednesday that one Iraqi child had died and 13 others were wounded.
The city has been put under a dusk-to-dawn curfew.
Gunmen have attacked a bus carrying Iraqi employees to the US base at Baghdad's international airport.
An employee quoted by Reuters news agency said the bus was riddled with bullet holes
She is quoted as saying there were at least 25 people in the bus when it was
fired on as it passed through a Baghdad suburb.
At least one person died in the attack.
Yarmouk hospital in central Baghdad said it had received several wounded, some of them in critical condition, Reuters said.
US-led forces have been battling a widespread insurgency in Iraq that has targeted the military as well as civilians seen to be collaborating with the foreign occupation of the country.