At least nine U.S. soldiers were killed Monday in a pair of deadly attacks north of Baghdad, U.S. military statements released Tuesday said.
"Six Task Force Lightning soldiers died as a result of injuries sustained following an explosion near their vehicles," a statement said. The attack took place during combat operations in Salah ad Din province.
Three other soldiers were wounded and taken to military treatment facilities.
In Diyala province, three more Task Force Lightning soldiers died when a bomb exploded near them, the military said. One other soldier was wounded.
The deaths brought to 3,176 the number of U.S. troops killed in the Iraq war. Seven American civilian contractors of the military also have died in the conflict.
On Monday, a suicide car bomber detonated explosives in a busy commercial district of Baghdad, killing 28 people and wounding 56 others, Baghdad police said.
The attack took place in a book market along Mutanabi Street at 11:45 a.m. (3:45 a.m. ET)
Mutanabi Street, named after a legendary 10th-century poet, once attracted Baghdad's intellectuals, who gathered at the bookshops for a lively exchange of ideas.
"Papers from the book market were floating through the air like leaflets dropped from a plane," a Health Ministry worker who was near the explosion told The Associated Press.
"Pieces of flesh and the remains of books were scattered everywhere," he told AP.
Meanwhile, in a series of deadly attacks, insurgents Monday targeted Shiite pilgrims in and around Baghdad on their way to Karbala for a religious commemoration.
At least nine people were killed and 24 wounded in separate attacks.
Tens of thousands of worshipers are en route to the holy city for Arbayeen, which is the commemoration of the killing of Imam Hussein. The observance falls on March 10 this year, at the end of the traditional 40-day mourning period following the anniversary of his death, known as Ashura.
Imam Hussein is revered by Shiite Muslims as the successor to the Prophet Mohammed.
A roadside bomb struck a group of pilgrims walking on the Mohammed al-Qassim Highway in eastern Baghdad, killing at least three and wounding 10 others, a Baghdad police official told CNN.
Others were shot and killed by gunmen in separate attacks in Baghdad, where many pilgrims are beginning the 50-mile (80-kilometer) journey on foot from Baghdad to Karbala.
U.S., Iraqi forces meet little resistance in crackdown
More than a thousand U.S. and Iraqi forces continued a massive clearing operation of the Sadr City area in eastern Baghdad on Monday. There have been no reports of any major resistance in the densely populated Shiite district, once a hotbed of sectarian violence.
The clearing operation, which is in its second day, is part of the new Baghdad security plan.
CNN's Jennifer Eccleston spent eight hours on patrol with Iraqi and U.S. forces on Monday in Sadr City, which is also the headquarters of the Mehdi Army, a militia loyal to radical Shiite cleric Muqtada al-Sadr.
"People were out shopping, children were playing soccer, playing football ... groups of young girls were walking around," she said. "I have been to Sadr City half a dozen times in three years, and I have never seen it so calm and seemingly normal."
Eccleston said residents told her they feel safer than they have in a long time and praised the Iraqi forces.
When asked about the American forces, residents said, "Well, they are helping out the Iraqis, and when that's done, they will go home," Eccleston reported.
On Sunday, the U.S. command in Baghdad said the joint operation in Sadr City is the largest security sweep of the neighborhood since the Iraq-led security plan, dubbed "Enforcing the Law," or "Fardh al Qanoon" in Arabic, was officially launched February 14.
No weapons caches were found or suspects detained during the operation, said Lt. Col. Scott R. Bleichwehl, a U.S. military spokesman. There were no incidents of violence and no casualties to coalition forces, Iraqi security forces or civilians during the sweep, he said.
Lt. Gen. Raymond Odierno, commander of the multinational corps in Iraq, speaking from Baghdad on Sunday, said he expects it will be "a minimum of six to nine months" before Iraqi forces will be able to maintain order in Baghdad.