One bomb exploded near a US convoy at 9.30am (0530 GMT) on Friday in the western Mansur district, witnesses said.
The bodies of several Iraqi civilians lay in the street after the attack on a US patrol.
Five Iraqis were injured and a US military Humvee vehicle was destroyed in the attack by a booby-trapped car, Iraqi police Major Muhammad Baghdadi told Aljazeera.
Baghdadi said US troops and Iraqi police cordoned off the site of the blast.
There was no word on casualties from the US military.
Another improvised device exploded in an eastern neighbourhood where US forces were also on patrol, killing one civilian and wounding three others, said a police official.
The blast shook the western neighbourhood.
A girl cries after her home was
destroyed by a car bomb
A third blast did not appear to cause any injuries, said Captain Talib Thamir. The US military confirmed the trio of attacks, but had no further information.
The blasts came one day after twin car bombs hit a highway police convoy, killing 14 people and wounding dozens.
The murder of a prisoner at a US-run Iraqi prison triggered a fight between detainees that left 12 injured, the second riot at the jail in two weeks, the US military said on Friday.
The fight broke out on Thursday night and was confined to detainees at Camp Bucca just outside the port city of Umm Qasr, the military said in a statement.
"The guards regained control of the compound and immediately began rendering medical treatment to 12 other detainees who were injured during the fight," said the statement.
"The fight was confined between the detainees in one compound and was not directed at US forces."
It said the remains of the murdered prisoner would be handed over to the Iraqi government and then returned to the family after the completion of an autopsy.
The prison houses 6000 detainees.
Also on Friday, the US military said a US marine was killed in a mortar attack on his camp in western Iraq.
Without giving details, the military statement said the attack occurred on Wednesday in Camp Hit in the al-Anbar province.
Aljazeera reported a Pakistani embassy official who disappeared more than five days ago in Baghdad was still alive.
A video on Friday showed Malik Mohammed Javed urging the Pakistani government and the international community to intervene and secure his release.
Javed urged the Pakistani
government to secure his release
The station said the captors, identified as being from the previously unknown group the Amuriya Brigade, made no demands for his release.
Pakistan urged the captors in Iraq to release Javed.
"We again appeal to Javed's kidnappers to free him in the name of Islam," Information Minister Shaikh Rashid Ahmad said on Friday.
"We appeal to them not to harm him because his aged parents and other family members have already suffered a lot."