In the third explosion on Tuesday, a bomb exploded outside a court in Baghdad when US soldiers were bringing prisoners out of the building.
Six people were injured, among them two policemen.
Police said the others wounded were prisoners brought to the Baghdad Court of Appeal in the city centre on charges such as murder and stealing.
The blast left a crater more than two feet deep in the pavement and shattered windows in the court.
No American soldiers were wounded, witnesses said.
Police said the prisoners were from the Abu Ghraib prison, a large jail on the western edge of Baghdad.
Children among casualties
Two other explosions rocked the southern city of Basra earlier on Tuesday.
Four Iraqis, among them two policemen, were killed in the first blast at a roadside in the centre of the city.
Nine people, including schoolchildren, were hurt according to police colonel Muhammad Khaziam al-Ali.
A British soldier stands guard at
the site of the explosion
A second blast echoed over downtown Basra about midday (09:00 GMT), an AFP correspondent reported, but it was not immediately known if there were further casualties.
"Some of the injured are school children. Boys and girls use this road early in the morning to go to school," said al-Ali, the head of internal security forces in Iraq's southern capital.
The first blast, a roadside bomb, blew up a civilian car and damaged two more cars.
British forces had cordoned off the area of the first blast, which included at least one school.
A crowd of angry Iraqis set a police station and the mayor's building ablaze in the town of Haditha, protesting against the alleged killing of an Iraqi girl during a raid by US troops.
Iraqis protested the alleged
killing of a child during a US raid
A US military spokesman in Baghdad said he had no information on the alleged killing in the town, which lies northwest of Baghdad on the way to the Syrian border.
Iraqi police opened fire on the crowd. Witnesses said the front of the major's building and a police station were on fire.
Meanwhile, the US-backed mayor of the Shia-populated Baghdad district of Sadr City, had been shot and killed in an altercation with American troops, the US military announced.
The US Central Command said the clash, which is now being investigated, took place at the building housing the district advisory council, of which Muhammad Ghazi al-Kaabi was chairman.
"This incident reportedly occurred as a result of a confrontation following Muhammad's refusal to follow instructions from the on-site security official, who was enforcing security procedures stemming from recent car bombing incidents in accordance with standard rules of engagement," the command said in a statement.
A shot fired during the altercation wounded the mayor in the lower extremities, the military said.
Although he was given immediate medical assistance on the scene of the incident and quickly taken to a US military hospital, al-Kaabi was pronounced dead upon arrival, according to the statement.
The command did not reveal who fired the shot. Nor did it offer any details about the nature of al-Kaabi's wounds.
US Central Command did not reveal who fired the shot that killed the mayor
A military occupation official contacted by telephone by AFP said he was unable to provide any further details.
It was not immediately clear what implications al-Kaabi's killing would have on the sprawling and politically sensitive Sadr City, which is home to two million Iraqi Shias.
Formally known as Saddam City, this part of the Iraqi capital was renamed after Ayat Allah Muhammad Baqir al-Sadr, a spiritual leader of Iraqi Shias, believed to have been assassinated by Saddam Hussein's government in 1999.