Four successive blasts hit the Iraqi city of Kerbala on Sunday, killing at least 17 people and wounding dozens more outside a local government building in an attack officials blamed on Al-Qaeda affiliates.
The first bomb ripped through a crowd of guards and civilians gathered in front of an office issuing ID cards and passports, and three other explosions went off shortly after as emergency services arrived to help the wounded, police said.
The blasts, three bombs in cars and explosives attached to a motorbike, tore the fronts off several homes and shops, leaving bodies among the rubble and twisted metal scattered across the street outside.
"I was inside my house when I heard a big explosion. When I got outside I saw many people wounded and some bodies on the ground," said Mohammed Na'eim, a local resident.
A Kerbala police official said 17 people were killed. Health department officials said 45 wounded were treated in Kerbala's main hospital and another 25 were sent to a hospital in the nearby city of Hilla.
Violence in Iraq has eased since the height of sectarian strife in 2006-2007, but insurgents tied to Al-Qaeda and Shi'ite militias still carry out daily attacks as US troops prepare to withdraw at the end of this year.
Mohammed al-Moussawi, chairman of the Kerbala Provincial Council, blamed Al-Qaeda affiliates for Sunday's attack.
Kerbala, a major Shi'ite holy city 80 km (50 miles) southwest of Baghdad, has often been attacked in the past by Sunni Islamist insurgents targeting Shi'ite pilgrims who flock to the city's religious sites.
Gunmen earlier this month attacked two buses carrying pilgrims heading for Kerbala, killing 22 men, and a suicide bomber targeting pilgrims killed four and wounded 17 on Thursday.
The bus attack in the Sunni heartland of Anbar province has fuelled worries about resurgent sectarian tensions. Violence killed thousands of people during bloodletting between Sunni and Shi'ite groups in Iraq in 2006-2007.
Insurgents this year have increasingly targeted local government buildings and the security forces in an attempt to destabilise Iraq's fragile government formed from Sunni, Shi'ite and Kurdish political blocs.
Bombers frequently set off one blast and trigger more when security officials arrive to help casualties.
Iraq's Al-Qaeda affiliates have been battered by the death of leaders and pressure from Iraqi and US forces. But security officials say there are signs insurgents are regrouping and returning to former strongholds.
More than eight years after the US invasion that toppled Saddam Hussein, the remaining American soldiers are scheduled to withdraw from Iraq at the end of this year when a bilateral security agreement with the OPEC oil producer ends.
US troop numbers in Iraq will have dropped to around 30,000 by the end of this month. They are mostly involved in advising and assisting Iraqi forces since ending combat missions last year.
Iraqi and US officials say local armed forces can contain the country's stubborn insurgency, but many Iraqis see some remaining American military presence as a guarantee of stability as their country works to rebuild from the war.
Iraqi Prime Minister Nuri al-Maliki's government is in talks with US officials over whether some American troops will remain on as trainers after 2011, but those negotiations are still in the preliminary stages.