A coordinated wave of car bombings tore through commercial streets in Baghdad on Saturday night, killing more than 30 and wounding dozens as insurgents kept up a relentless offensive during the holy month of Ramadan.

The blasts struck in Shia Muslim areas of the Iraqi capital. Although there was no claim of responsibility, coordinated bombings against Shias are a favorite tactic of al-Qaeda’s Iraq branch.

The explosions were all caused by car bombs timed to go off after the breaking of the daily Ramadan fast when many people are out shopping or relaxing in coffee shops, police said.

Bombings and other attacks have killed more than 230 people since the start of Ramadan on July 10, 2013. The violence is a continuation of a surge of bloodshed that has been rocking Iraq for months, reviving fears of a return to the widespread sectarian bloodshed that pushed the country to the brink of civil war after the 2003 U.S.-led invasion.

Saturday’s blasts began with an explosion in a busy shopping street that shook buildings in the central Baghdad neighborhood of Karrada. Police say that attack killed nine and wounded 17, and left several shops and food stalls damaged.

It was followed by similar car bombs that struck the northwestern Tobchi district, killing eight and wounding 29, and Baiyaa in western Baghdad, killing three and wounding 13, authorities said.

Another blast struck Zafaraniyah in southeastern Baghdad, killing six and wounding 15, officials said. Yet another exploded near a bakery in the New Baghdad neighborhood in the southeast, killing three people and wounding 11, authorities said.

Another car bomb exploded in a Shia part of the religiously mixed western neighborhood of Shurta, a mainly Sunni area, killing four and wounded 12, authorities said.

The official, Bassem Mahmoud, headed a Sunni group known as Sahwa, which joined the fight against al-Qaeda during the height of Iraq war.

Police provided details of the attacks, while hospital officials confirmed the death tolls. All officials spoke on condition of anonymity because they are not authorized to talk to media.

These attacks came only a day after a deadly bombing at a Sunni mosque in Diyala killed 22 people and wounded dozens.

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