The bombings shattered a period of relative calm in the Iraqi capital, raising to at least 306 the number of Iraqis killed in what has been one of the least deadly months for both Iraqi civilians and U.S. troops since the war began. Seven American troops have been killed - the lowest monthly total since the war started in March 2003, according to an AP tally.
The attack also underscores concerns about the abilities of Iraqi security forces to maintain security gains now that U.S. troops have withdrawn from major urban areas. Some Sunni insurgents still seek to re-ignite sectarian violence with the majority Shiites and reverse Iraq's security gains in the past two years.
Iraqi police told CBS News' Baghdad bureau that a total of four bombs had exploded at four different mosques. The first blast took place at a mosque loyal to anti-U.S. cleric Muqtada al-Sadr, according to the police source.
The officials all spoke on condition of anonymity because they were not authorized to release the information.
The deadliest attack Friday came when a car bomb exploded near a Shiite mosque in the northern Baghdad neighborhood of Shaab, killing at least 24 people and wounding 17 others, said two Iraqi police officials and a medical official.
At about the same time, almost simultaneous explosions struck near the al-Rasoul mosque near the Jisr Diyala bridge, in southern Baghdad, killing four worshippers and wounding 17 others, the two police officials said.
A roadside bomb exploded near al-Hakim mosque in Kamaliyah area in eastern Baghdad, wounding six worshippers. A bomb near Imam al-Sadiq mosque in the religiously mixed neighborhood of Ilam in southwestern Baghdad wounded 4, while a bomb near the al-Sadrain mosque in the Zafaraniyah area in southeastern Baghdad killed one and wounded seven worshippers.
The officials giving the toll all spoke on condition of anonymity because they were not authorized to release the information.
Only three other months this year saw fewer Iraqis killed since the AP began tracking war-related fatalities in May 2005. There were 242 deaths in January, 288 in February and 225 in May.
But U.S. commanders say security gains are fragile and reversible, and the Iraqi government needs years of further assistance.
U.S. commanders have also warned attacks could escalate ahead of national elections next year. The United States has about 130,000 forces in Iraq, with current plans calling for most combat forces to remain in the country until after the Jan. 16 vote.
Then, under a timeline set by President Barack Obama, all combat troops will withdraw from Iraq by August 2010.
American troops, though, continue to be targeted by insurgents. On Friday, rockets struck a U.S. base outside Iraq's second largest city of Basra, but there were no reports of casualties. Three U.S. soldiers were killed earlier this month in a similar attack at the base.
Questions about the Iraqi security forces were heightened earlier this week, when they clashed violently with residents of a camp north of Baghdad for exiled Iranians. Iraqi officials confirm at least seven people were killed and spokesmen for the exiles say 12 were killed and hundreds more injured in two days of intense skirmishes.
On Friday, an American military medical team went to Camp Ashraf and evacuated some of the camp's residents who were wounded in the clashes, which began Tuesday when the Iraqis tried to enter the camp to establish a police station inside its fences.
The U.S. military and embassy officials did not immediately respond to questions about how many the medical team evacuated from the camp or where they were taken.
The violence at the camp, which was until earlier this year guarded by the U.S. military, has raised human rights issues and questions about how Iraq will balance its relations with the U.S., which has called for restraint, and neighboring Iran, which wants the exiles sent back.
About 3,500 ex-Iranian fighters and their relatives live in the camp, first set up in 1986 when they helped Saddam Hussein in the Iraq-Iran war. After the U.S. invasion of Iraq in 2003, American troops disarmed the fighters and confined them to the camp. The Americans handed over responsibility for the camp to the Iraqis on Jan. 1, but maintain a force nearby.
Iraq has said it wants to close the camp, but human rights groups fear the Iranians could be subjected to punishment or even death if they are sent back to Iran.
A camp resident, Hossein Madani, 49, said U.S. military medics entered the camp Thursday night and left Friday morning, taking with them a handful of injured residents.
"There were thousands of American forces here before. They should come back and take control of the situation," said Madani, who has lived with his wife in the camp for seven years.
Meanwhile, Iraqi police Friday announced they had recovered millions of dollars stolen from a state-run bank in a robbery that left eight guards dead.
Interior ministry spokesman Maj. Gen. Abdul-Karim Khalaf said all the money was recovered and added that police have detained some of the robbers.
He did not provide further details.
Gunmen killed eight security guards at the Rafidain Bank, making off with nearly $7 million. Police said the robberies appeared to be the work of militants seeking money for operations after their funding was severely curtailed in U.S.-Iraqi military crackdowns.
Police found the money Thursday when they raided the house of an Iraqi soldier, said an interior ministry official, who spoke on condition of anonymity because he was not authorized to release the information.