A bomb hit a motorcade carrying the wife of Iraq's first lady through Baghdad on Sunday, while the U.S. military said a roadside explosion killed four Marines in the deadliest attack in western Anbar province in months.

The motorcade bombing in Baghdad's Karrada district injured four of Hiro Ibrahim Ahmed's bodyguards but left her unharmed, according to the office of her husband, President Jalal Talabani.

She was headed to the city's central National Theater to attend a cultural festival when the attack occurred just before noon, said the presidential office. It was unclear if she was the target or if the bombing was random.

The four Marines were killed in Anbar province on Friday, but no other details of the incident were released.

Anbar was once a stronghold for insurgents battling against U.S. forces. But in the past year the vast desert province has largely been calmed with the rise of the Awakening Council movement — Sunni fighters who now turn their guns on Al Qaeda instead of U.S. forces.

Friday's attack was the most lethal in the province since Sept. 6, when four Marines were killed in combat. The military did not release details of those deaths either.

On April 22, two Marines were killed in Anbar when a bomb-rigged truck exploded at a checkpoint in the city of Ramadi.

Despite new reports of violence, military spokesman Rear Adm. Patrick Driscoll told reporters on Saturday that attacks carried out by Al Qaeda declined last month after increasing earlier this year.

He said there was "no place for Al Qaeda" to hide in Iraq and U.S. troops were continuing to hunt them down in Diyala province and the city of Mosul, where many are believed to have fled north from Baghdad.

Meanwhile, Iraqi health officials said at least 10 people — including two children — were killed in the past 24 hours in the Baghdad neighborhood of Sadr City, a slum of 2.5 million people and a stronghold for the Mahdi Army militia led by anti-American cleric Muqtada al-Sadr.

Officials at two hospitals in Sadr City spoke on condition of anonymity for security reasons.

U.S. and Iraqi forces have been battling militia members there for weeks as part of an Iraqi government crackdown on the fighters.

Iraqi government spokesman Ali al-Dabbagh said the battles against the militia fighters in Sadr City would continue.

"It is the full responsibility of the Iraqi government to implement the rule of law," al-Dabbagh said.

The clashes with Mahdi Army have caused deep rifts among Iraq's Shiite majority and have pulled U.S. troops into difficult urban combat.

Militia members have been blamed for firing hundreds of rockets or mortars from Sadr City into the Green Zone, the U.S.-protected area housing the American embassy and much of the Iraqi government. In the past month, more than a dozen people — including two American civilians and soldiers — have been killed inside the zone during the attacks.