A car bomb has killed at least 55 people and injured about 70 in the Iraqi city of Karbala, in the second such attack in two weeks.
The bomb caught people in the street heading for prayers
The city houses two of Shia Islam's holiest shrines and reports say the bomb went off on a busy street as people headed to pray.
The bomb exploded near the golden-domed mosque of the Imam Abbas shrine
Meanwhile, nine US soldiers were killed in Iraq in the past two days, the US military said.
On Friday three soldiers and two Marines were killed during combat operations in Anbar province, west of Baghdad.
Three US soldiers were killed and another wounded by a roadside bomb south-west of Baghdad on Saturday.
Another soldier was killed and two were wounded when their patrol was struck by a roadside bomb, also south of the capital.
Iraqi television images from Karbala showed a man running down a smoke-filled street holding a lifeless baby above his head.
Ambulances had rushed to the scene, in a crowded area full of shops and restaurants in the city, 100km (70 miles) south-west of Baghdad.
Angry people gathered at the blast site, many of them searching frantically for missing relatives, the Associated Press news agency reported.
Some began to throw stones at the police, accusing them of failing to protect the people.
Police fired weapons in the air to disperse the crowds, the agency says.
Karbala is the second most important shrine city for the Shia, the BBC's Andrew North reports from Baghdad.
He notes that attacks on shrines have become a hallmark of extremist Sunni Muslim groups, particularly al-Qaeda.
The group claimed responsibility for the bombing last year of another major Shia shrine, in Samarra, which sparked the sectarian violence that has torn through the country ever since, our correspondent adds.
A suicide bomber killed at least 42 people in Karbala on 14 April.
Earlier, the powerful Shia cleric, Moqtada al-Sadr, criticised US President George W Bush for refusing to establish a timetable for a US troop withdrawal from Iraq.
In a statement read out on his behalf in the Iraqi parliament, the cleric said the situation in Iraq could not be any worse following an American pull-out than it was already.