More than 30 people have been killed and scores hurt in a wave of car blasts in Baghdad, Iraqi officials say.
The earlier blasts took place in a largely Shia area of Baghdad
An attack near a Sunni mosque in northern Baghdad killed at least 15 and wounded 35, medical officials said.
Earlier, at least 15 people died and 60 were wounded in a triple bombing on a busy market street in the south-west of the capital, officials said.
The US military in Iraq said three of its soldiers had been killed in more bombings just outside Baghdad.
The total number of US military deaths in Iraq is said to have reached 2,972 since the US-led invasion of the country in 2003, according to Pentagon figures.
Many commentators believe this to be a symbolic milestone, as it is close to exceeding the number of people who were killed in the 9/11 attacks - 2,973.
Those attacks launched the Bush administration's so-called war on terror.
The blast by the mosque came hours after the attack on a busy market street in the Bayaa district.
The Bayaa strike was severe, even by Iraqi standards, the BBC's Peter Greste reports from Baghdad.
It is not clear who was targeted, but almost all the victims were civilians.
Cars were parked close to one another in an area packed with shops and known for buying and selling vehicles.
One exploded as shoppers milled about in the late-morning sunshine.
As rescuers rushed to help the victims, a second and then a third bomb went off.
In the east of the city, an improvised explosive device exploded near a Sunni shrine.
Again, as police and emergency services rushed in, two more bombs exploded killing one police officer and wounding nine more.
In the southern city of Basra, the council has said it is withdrawing its co-operation with the UK military in the area in protest at a raid on a police headquarters in Basra.