BAGHDAD, Iraq, (AP) – A series of bombings struck predominantly Shiite areas in Baghdad on Sunday, killing at least seven people and wounding dozens, police said, as insurgents persist in their relentless bid to terrorize the capital in the final days before U.S. and Iraqi soldiers plan to begin a massive crackdown.

More than 150 people, mostly Shiites, have been slain in bomb attacks in the last week as the majority Islamic sect in Iraq celebrates a 10-day festival leading up to one of their holiest days, Ashoura.

Iran, meanwhile, closed several border crossings with Iraq for Ashoura, which culminates on Tuesday with processions and ceremonies, including self flagellation, to mark the Shiite saint Imam Hussein’s death in a battle.

The violence Sunday started at about 7:30 a.m. when a bomb struck a minibus carrying people to a predominantly Shiite neighborhood in Baghdad on Sunday, killing one passenger and wounding five, police said.

The explosive device was hidden in a bag left by a passenger who got off the bus before it detonated in the Baladiyat neighborhood in eastern Baghdad. The bus was heading to the adjacent Shiite district of Sadr City, which has been targeted several times in the past.

A parked car bomb exploded in an intersection near an outdoor market in the Sadr City district about five hours later, killing at least four people, two of them women, and wounding 39, police said. The sprawling Shiite slum is a stronghold of the Mahdi Army that is loyal to radical cleric Muqtada al-Sadr and has blamed for much of the country’s spiraling violence.

About five minutes later, a bomb hidden in a bag exploded in an outdoor market in the Baiyaa neighborhood in western Baghdad, an area that is mostly Shiite, although a significant number of Sunnis live there. At least two people were killed and 17 were wounded, including two children, police said.

Elsewhere, a car bomb exploded near a mosque in the Sunni city of Fallujah, 40 miles west of Baghdad, killing two civilians and wounding four, police said.

Meanwhile, Iranian state television, citing the government in Tehran, said the crossings were closed to “contain the large number of pilgrims” bound for the Shiite holy city of Karbala in southern Iraq who were planning to cross into Iraq without “legal documents.”

No other details were given but the report indicated that not all border crossings had been closed and that some pilgrims were allowed through elsewhere.

An official with the Iraqi border forces, who spoke on condition of anonymity because he was not authorized to talk to the media, said the closures involved the border checkpoint of Sheeb, in Maysan province, and the Shalamjaa border checkpoint in Basra province.

The official said the crossings had “closed for the citizens of both countries, Iraq and Iran, because of Ashoura, until further notice” but that the border checkpoints remained “open to dealers of foodstuff only.”

The Shalamjaa crossing is a route most frequently used by pilgrims traveling from the predominantly Shiite Iran to the Shiite holy city of Karbala, 50 miles south of Baghdad, the Iraqi capital and the center of the commemorations on Ashoura.

Also Sunday, drive-by shooters killed a high-ranking Shiite official at the Iraqi industry and mines ministry, along with his 27-year-old daughter and two other people.

Insurgents have frequently targeted high-ranking Iraqi officials who are seen as collaborators with the U.S. forces.

Last Wednesday, Iraq’s higher education minister, a Sunni, escaped an assassination attempt after gunmen opened fire on his motorcade as he was traveling in southern Baghdad, killing one of his guards and seriously wounding another.

The U.S. military reported the deaths of seven more soldiers on Saturday — two in Diyala province northeast of the capital on Friday, three in an unspecified location north of Baghdad on Saturday and two in east Baghdad on Thursday.

The latest reported deaths raised to at least 3,079 the number of U.S. service members who have died since the beginning of the Iraq war in March 2003, according to an Associated Press count. The figure includes seven military civilians. At least 2,471 died as a result of hostile action, according to the military.

Also Saturday, two 19-year-old wrestlers who were twin brothers also were killed in by a roadside bomb Saturday while driving in the predominantly Sunni neighborhood of Azamiyah in northern Baghdad, police said.

Ahmed and Bakir Mustafa were the latest sports figures to perish in the sectarian violence that has been striking Baghdad, although police said it appeared the bomb was targeting Iraqi or U.S. security forces and not the wrestlers. A boxer also was found dead last week with marks on his neck indicating he had been hanged.

“It is a great loss for me as a father and for Iraq to have lost two young wrestlers,” said the young men’s father, who also is coach of the Iraqi wrestling team.