on Firiday, the bomber attacked the Baratha mosque barely an hour before Friday's prayers, a security source said on Friday.
The mosque, which is used by members of Iraq's Shia, had been fired at several times since the 2003 US-led invasion of Iraq.
On April 7, a triple bombing hit worshippers just as they were leaving the mosque, killing 90 and wounding 175.
Also, a mortar barrage struck a commercial area north of Baghdad on Friday, killing at least two people and wounding 16, police Lieutenant Muhammad Khayun said.
The attack occurred at 1:30pm on a street with many shops in the northern suburb of Saba Abkar, near the Taji air base.
US soldiers missing
Two US soldiers were missing and one was killed after their team was attacked at a traffic-control point southwest of Baghdad, the Pentagon said on Friday.
After hearing small arms fire and explosions in the vicinity of the checkpoint southwest of Yusufiya, a quick reaction force responded to the scene, a Pentagon statement said out of Baghdad.
"Coalition forces have initiated a search operation to locate and determine the status of the soldiers," the statement added, saying the incident occurred about 7:55pm local time.
Also on Friday, the US military said a probe of allegations that marines killed up to 24 unarmed civilians in the town of Haditha last year has been completed and a top commander is reviewing it.
Lieutenant-General Peter Chiarelli, commander of US ground forces in Iraq, received the findings of the investigation and would either approve the findings, add his own conclusions or request more information from the investigating officer.
Friday's attack on a Shia mosque
in Baghdad left 10 people dead
A separate investigation being conducted by the Naval Criminal Investigative Service could lead to charges including murder.
Major-General Eldon Bargewell led the fact-finding mission looking at not only whether marines involved in the November 19 incident lied about what happened, but whether senior US Marine Corps officers sufficiently examined the veracity of the troops' account.
Friday's violence came despite a clampdown in the capital ordered by prime minister Nuri al-Maliki since Wednesday that saw vehicles banned from the capital's streets during prayer times, and a large number of Iraqi and US soldiers out on patrol.
The crackdown, dubbed Operation Forward Together, is one of the largest since the US-led invasion of 2003 and is directed at exploiting any power vacuum in anti-US and US backed Iraqi government fighters' ranks after the death of Iraq al-Qaeda frontman Abu Musab al-Zarqawi in a US air raid last week.
It follows similar counter operations after the two previous prime ministers, Iyad Allawi and Ibrahim al-Jaafari, took power.
In Baquba, a mother and four of
her children were killed
The defence ministry said 160 additional checkpoints had been set up in Baghdad and 26,000 Iraqi soldiers, 23,000 Iraqi police and 7,200 coalition troops were deployed on the streets.
The security plan includes house-to-house searches in areas suspected of harbouring anti-government fighters as well as a crackdown on civilians carrying weapons.
Outside the capital too, violence raged on Friday.
Just south of Baghdad, in an area dubbed the Triangle of Death, for the frequency of attacks, four people were killed and 10 kidnapped in separate incidents, police said.
In the city of Baquba, north of the capital, a woman and her four children were killed overnight when a bomb went off in a neighbour's house, police said.
End of al-Qaeda?
The US military said on Thursday it had killed 104 anti-government fighters and captured 759 in a total of 452 operations since al-Zarqawi's death.
Muwaffaq al-Rubaie, Iraq's national security adviser, said it was the beginning of the end of al-Qaeda in Iraq.
"We believe al-Qaeda in Iraq was taken by surprise; they did not anticipate how powerful the Iraqi security forces are and how the government is on the attack now," he said.