BAGHDAD, Iraq (CNN) -- Seven Shiite pilgrims were gunned down Sunday in a town south of Baghdad, an Interior Ministry official said.
The attack occurred at 3 p.m. in Salman Pak when the pilgrims were walking to Kadhimiya in northwestern Baghdad to commemorate the death of revered figure Imam Moussa al-Kadhim, the official said.
The pilgrims, all males, were carrying black flags and chanting religious songs before the attack, the official said.
Authorities are searching for the assailants, the official said.
Salman Pak -- also referred to as al-Madaen -- is a predominately Sunni town. It was controlled by al Qaeda in Iraq before the Iraqi security forces managed to gain control of much the area. Still, there are al Qaeda in Iraq cells in villages around the town.
Over the past few days, hundreds of thousands of Shiite pilgrims started walking toward Kadhimiya, a Shiite neighborhood, for the annual commemoration of al-Kadhim's death. Many have traveled -- either by foot or by car -- from across the country, especially southern Shiite provinces.
Brig. Gen Qassim Atta, spokesman for the Baghdad security plan, said at a news conference Sunday, "A large number of security forces have deployed to provide security for the pilgrims by establishing checkpoints and by sending foot patrols and preparing additional forces to deal with emergencies."
Atta said people going into Kadhimiya are not allowed to carry weapons, bags, cell phones or any type of communication devices like radios.
He also warned pilgrims about taking food or drinks from people they don't know and not to believe rumors about suicide bombers. During the pilgrimage in 2005, about 1000 pilgrims died in a stampede that grew from a rumor of a suicide bomber.
Atta said he has more than 200 women conducting searches in Kadhimiya because of a rise in female suicide bombers.
The Imam Moussa al-Kadhim's shrine is one of Shiite Islam's holiest sites.
Also Sunday, a local politician and his son were wounded and two of their guards were killed in a bomb blast Sunday in Iraq's Anbar province, an Interior Ministry official said.
The bomb exploded at the home of the politician, Zaki al-Obaid, who leads the local branch of the Iraqi Islamic Party, according to a news release from the Sunni political group.
"This heinous crime came in a series of crimes targeting the leaders of the Islamic Party in Iraq in general and particularly in Anbar province," the news release said. "The Iraqi Islamic Party condemns and denounces this cowardly act."
Anbar province used to be dominated by al Qaeda in Iraq, but Awakening Councils began to take over the province two years ago. Awakening Councils, whose members are predominantly Sunni, have been recruited by the U.S. military to work against al Qaeda in Iraq and other militias.
The councils became the main rival of the Iraqi Islamic Party in Anbar after working to provide security and stability to the province.
In the past year, a number of Iraqi Islamic Party members were killed or wounded.
In another incident Sunday, a civilian was killed in clashes between police and members of an Awakening Council in al-Fadhi, a Sunni district in central Baghdad, an Interior Ministry official said.
Three people also were wounded in the clashes that occurred at about 2 p.m. The official said victims were caught in the crossfire. The Iraqi Interior Ministry is investigating the incident.
U.S.: Iraqi civilians killed by soldiers were unarmed
Investigators have determined three Iraqi civilians were unarmed and attacking no one when U.S. soldiers fatally shot them in western Baghdad last month, the U.S. military said Sunday.
U.S. military officials initially said at least one of the three Iraqis, who were riding in a car approaching the soldiers, started shooting, and that the soldiers returned fire. The military also initially said a weapon was later found in the car, and bullet holes were found in two of the soldiers' humvees.
But an investigation found the soldiers shot and killed three "law abiding citizens of Iraq," and that no weapon was found in the vehicle, a military release stated.
Also, the investigation determined only one humvee had a bullet hole, and that the bullet hole's source isn't known, said Lt. Steve Stover, a military spokesman.
Still, investigators determined "neither the soldiers nor civilians involved in the incident were at fault," the release said.
"This was an extremely unfortunate and tragic incident," said Col. Allen Batschelet, chief of staff for Multi-National Division-Baghdad. "Our deepest regrets of sympathy and condolences go out to the family.
"We are taking several corrective measures to amend and eliminate the possibility of such situations happening in the future."
The shooting happened June 25 in the civilian area of Baghdad International Airport. U.S. soldiers "perceived the rapidly approaching vehicle as a threat" and opened fire "after the driver failed to respond to soldiers' warning measures," according to the military statement.
The Iraqi Interior Ministry countered the U.S. military's initial account of the incident, saying U.S. soldiers killed a male banker and two female employees as they were driving to work.
On Sunday, the U.S. military said its initial account "resulted from the numerous soldier witnesses who strongly believed they were being fired upon from the vehicle."
During initial questioning, the soldiers in the convoy said they "felt threatened and believed they saw flashes coming from the front passenger window," Stover said.
The military also said Sunday its initial report about a weapon in the victims' car came from a mistaken belief that Iraqi police had found one.
Mohammed Hafez, son of the slain bank director, said he was shocked by the findings of the investigation.
"My father was a good man. He was a very good man," he said. "I lost not only a father, he was also my friend."
The platoon involved in the incident was banned from conducting military operations during the course of the investigation, Stover said. The platoon returned to duty about two weeks ago after the investigation was approved.
Hafez said he wants the soldiers to stand trial. He said the U.S. military has apologized to his family, meeting with them twice and offering them $10,000 and a condolence letter. Hafez said his family turned down the money.
Stover confirmed the meetings, but not the offer of money.
CNN's Mohammed Tawfeeq and Jomana Karadsheh contributed to this report.