BAGHDAD, Iraq (CNN) -- A suicide bomber attacked Shiite pilgrims Thursday evening as they traveled to a festival, killing 18 people and wounding 75, an Iraqi Interior Ministry official said.
The woman's attack took place in the Iskandariya district south of Baghdad.
The pilgrims were traveling to Karbala, about 60 miles southwest of the Iraqi capital.
Earlier Thursday, coalition troops in Baghdad killed a man during a raid targeting al Qaeda in Iraq, the U.S. military said.
The incident occurred during an operation that led to the capture of an al Qaeda suspect "believed to conduct financial transactions for AQI and its car-bombing networks," the U.S. military said.
Troops killed the man when he "refused to comply with their instructions and made threatening movements toward them." Two other people were detained.
On Wednesday, a U.S. soldier and an Iraqi interpreter were killed when their vehicle was struck by an improvised explosive device in northwest Baghdad, military officials said in a statement.
The incident occurred about 10:10 a.m. (3:10 a.m. ET), the statement said.
The soldier was assigned to Multi-National Division -- Baghdad. The soldier's name was withheld pending notification of relatives, officials said.
The death brings to 4,141 the number of U.S. service members killed since the Iraq war began in March 2003.
CNN's Mohammed Jamjoom contributed to this report.