BAGHDAD: Bombs exploded near five Shiite mosques in Baghdad, killing at least 29 people, in an apparent coordinated attack that targeted worshippers leaving Friday prayers, Iraqi police and hospital officials said.

The bombings shattered a period of relative calm in the Iraqi capital, raising to at least 306 the number of Iraqis killed in what has been one of the least deadly months for both Iraqi civilians and US troops since the war began.

Seven American troops have been killed — the lowest monthly total since the war started in March 2003, according to an AP tally.

The attack also underscores concerns about the abilities of Iraqi security forces to maintain security gains now that US troops have withdrawn from major urban areas.

Some insurgents still seek to re-ignite sectarian violence and reverse Iraq’s security gains in the past two years.

The deadliest attack Friday came when a car bomb exploded near a mosque in the northern Baghdad neighborhood of Shaab, killing at least 24 people and wounding 17, said two Iraqi police officers and a medical official.

At about the same time, almost simultaneous explosions struck Al-Rasoul Mosque near the Jisr Diyala bridge, in southern Baghdad, killing four worshippers and wounding 17, the police officers said. A roadside bomb exploded near Al-Hakim Mosque in the Kamaliyah area in eastern Baghdad, wounding six worshippers. A bomb near Imam Al-Sadiq Mosque in the religiously mixed neighborhood of Ilam in southwestern Baghdad wounded four, while a bomb near Al-Sadrain Mosque in the Zafaraniyah area in southeastern Baghdad killed one and wounded seven worshippers.

Only three other months this year saw fewer Iraqis killed since the AP began tracking war-related fatalities in May 2005. There were 242 deaths in January, 288 in February and 225 in May.

But US commanders say security gains are fragile and reversible, and the Iraqi government needs years of further assistance.