A suicide car bomb exploded near an Iraqi army patrol stationed in central Baghdad, killing at least two Iraqi soldiers.
The bomb was detonated at around 1 pm (1000 GMT) near the Andalus square which is close to the headquarter of the Iraqi Army, said a police source who refused to name himself.
However, a witness said, three Iraqi soldiers and one civilian were killed in the blast.
A series of car bombs exploded in separate areas of the Iraqi capital here in the day, all targeting US and Iraqi troops.
Police sources said earlier that one bomb occurred in northern Baghdad, killing six and wounding 15 and destroying some vehicles.
Another bombing attack took place in south Baghdad when a suicide bomber detonated his vehicle near an Iraqi army convoy, injuring 5 Iraqi soldiers and three civilians, an interior ministry official said.
Meanwhile, a bomber also wounded two US soldiers when he attacked their vehicle in the southeast of the capital, said media reports.
However, US forces and Iraqi authorities could not immediately be reached for official confirmation.