Hadi Mizban / AP
Victims of Thursday's car-bombing in Iraq were returned from the Shiite festival of Arbaeen, which is shown in Karbala.
Updated at 1:30 p.m. ET -- A car-bomb explosion tore through a crowd of Shiite pilgrims returning home Thursday from a religious commemoration, killing at least 27 and reinforcing fears of renewed sectarian violence, according to Iraqi officials.
The blast erupted late in the afternoon in the town of Musayyib, about 40 miles south of the Iraqi capital. It targeted worshipers returning from the Shiite holy city of Karbala following the climax of the religious commemoration known as Arbaeen.
Children were among the 20 people confirmed killed, according to a police official. At least 60 people were wounded.
The bomb went off in the middle of a gathering of pilgrims changing buses coming from Karbala on their way to other destinations in the country, according to police.
"The explosion shook the whole block and smashed the windows of my house," said teacher Ibrahim Mohammed, who lives nearby. "I ran to the scene of the explosion only to find charred bodies and burning cars. There were women screaming and searching for their missing children."
Ali Sabaar, a pilgrim who said he witnessed the explosion, also described a horrific scene.
"I was getting a sandwich when a very strong explosion rocked the place and the blast threw me away," he said. "When I regained my senses and stood up, I saw dozens of bodies. Many cars were set on fire. I just left the place and didn't even participate in the evacuation of the victims."
A deadly car bombing in Baghdad in December was part of a recent wave of violence in Iraq had killed at least 26 people across the country by late in the month. NBCNews.com's Dara Brown reports.
A hospital official confirmed the casualty toll. The officials spoke on the condition of anonymity because they were not authorized to release the information to reporters.
Thursday marked the height of Arbaeen, when hundreds of thousands of Shiite pilgrims converged on Karbala to mark the passing of 40 days after the anniversary of the seventh century martyrdom of the revered Shiite saint Imam Hussein, the grandson of the Prophet Muhammad.
Shiite pilgrims are one of the favorite targets for Sunni insurgents during Shiite religious events.
Iraqi authorities typically tighten security in Karbala and along routes used by pilgrims, but security forces acknowledge they are unable to prevent all attacks.
As in previous years, the pilgrims practiced the ritual of self-flagellation on the streets, hoisted Shiite religious flags on trees and lamp posts and served food from tents pitched on street corners.
Zaid Mohammed, a 21-year old student, said he walked to Karbala from a nearby city to show his deep respect for Imam Hussein.
"All the people came here to show their gratitude and appreciation for the sacrifices made by Imam Hussein while fighting injustice," he said. "We have decided to confront all the security risks that we might face on our way to Karbala."
State television earlier Thursday aired video of Prime Minister Nouri al-Maliki walking among the pilgrims.
Arbaeen has been a frequent target for militants since the U.S.-led invasion that toppled Sunni dictator Saddam Hussein, who banned Shiite festivals.
The latest violence followed nearly two week of protests against Maliki by thousands of people from the minority Sunni community in the western province of Anbar.
The Associated Press and Reuters contributed to this report.
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