(CNN) -- Three attacks targeting Shiite pilgrims killed 21 people and wounded dozens Thursday in Baghdad, police said. And in other violence in Iraq, eight people were killed.
A suicide bomber blew himself up among pilgrims in western Baghdad's Mansour district, killing 11 other people and wounding others, police said.
Separately, in eastern Baghdad's Nahdha commercial district, a suicide car bomb targeting civilians killed eight people in addition to the bomber and wounded 13 others, police aid.
In northeastern Baghdad's Ur, a car bomb targeting Shiite pilgrims killed two people and wounded eight, police said.
Pilgrims from across the country have been headed to the Imam Kadhim shrine in Baghdad's Kadhimiya neighborhood. The event culminates Saturday when the faithful commemorate the death of Imam Moussa al-Kadhim, one of 12 revered imams in Shiite Islam.
Thousands of Shiite pilgrims have been killed or wounded in attacks over the past decade.
Meanwhile, seven people were killed Thursday and 12 others wounded when the Iraqi army shelled areas in Falluja, west of Baghdad, health officials said. More than 300 people have been killed in Falluja this year, most of them civilians, the officials told CNN.
Also, a roadside bomb exploded Thursday on an Iraqi police patrol, killing the head of a local police station in al-Rashdiya on the northeastern outskirts of Baghdad. Another two police officers were critically wounded, according to police officials in the Iraqi capital.