A police spokesman said at the scene at least one Iraqi had been killed when a rocket hit a street in the Mansur neighbourhood of western Baghdad.
At least two loud blasts rang out around Baghdad's Green Zone, one of Saddam Hussein's former palace complexes where the US-led occupation's administration in Iraq is based.
The blasts were heard shortly before 10am (07:00 GMT).
A senior US officer said the blasts were probably rocket impacts.
Police said they believed three rockets or mortar rounds had been fired from the south of the city towards the Green Zone.
Meanwhile, a rocket attack near the flashpoint Iraqi town of Falluja, west of Baghdad, killed two US soldiers and wounded seven, the US occupation forces said on Sunday.
Brigadier General Mark Kimmitt, deputy director of operations for the US army in Iraq, said three rockets hit a forward operating base and two impacted outside at about 8pm (17:00 GMT) on Saturday. The wounded comprised six from the army and one from the navy, he said.
The attack brought to 395 the number of US troops killed in action in Iraq since the US-led invasion a year ago.