Iraqi authorities banned motorcycles from Baghdad's streets and dispatched tens of thousands of security forces to guard a Shiite pilgrimage Thursday after coordinated car bombings targeted processions across the country the day before, killing 72 people in one of the worst attacks since the U.S. troops withdrawal.

Despite the violence, hundreds of thousands of faithful Shiites continued their marches to commemorate a revered saint. The processions of pilgrims carrying green banners filled roads into and around the capital as they made their way toward the twin-domed shrine in Baghdad's Kazimiyah neighborhood where Imam Moussa al-Kadhim is said to be buried.

"The events that took place yesterday will never undermine our determination to go to commemorate Imam al-Kadhim," vowed pilgrim Sayid Ali Jassim, standing near a security checkpoint where heavily armed soldiers peered out from behind barriers.