Police said four blasts struck the procession in the town of Dujail, located some 50 (80 kilometers) miles north of Baghdad. Six people were also wounded in the attack, police and hospital officials said.
Two more bombs were discovered and disarmed before they exploded, said a local police official who spoke on condition of anonymity because he was not authorized to brief the media.
Earlier, a roadside bomb wounded three pilgrims in the downtown Baghdad neighborhood of Karradah, police said.
Shiite pilgrims from across Iraq are headed to the holy Shiite city of Karbala for Ashoura, which marks the seventh century death of Imam Hussein in a killing that sealed Islam’s historic Sunni-Shiite split.
Provincial spokesman Saeed Mohammed Saeed estimated that three million Shiites are expected to converge on Karbala, south of Baghdad, by the time Ashoura peaks on Friday morning after a night-long ritual of prayers, speeches and self-flagellation.
Many of the pilgrims march on foot to Karbala, and are frequently targeted by Sunni insurgents who seek to re-ignite sectarian violence in Iraq.
In violence unrelated to the pilgrimage, gunmen killed public officials in three separate Baghdad shootings.
Police said the slaying of an Education Ministry senior official and his wife, Electricity Ministry spokesman Aziz Sultan, and an employee of the quasi-public Sunni Endowment religious group did not appear to be related.
City police and hospital officials confirmed all three killings on condition of anonymity because they were not authorized to brief the media. Government and security officials have been frequent targets since March elections failed to produce a clear winner, giving insurgents an opportunity to seize on Iraqi frustrations over the political impasse.
Prime Minister Nouri Al-Maliki expects to announce his new Cabinet next week.
Meanwhile, police and hospital officials in the northern city of Mosul said a civilian was killed in a drive-by shooting, but the motive of the attack was unknown.
