Four separate explosions shock Baghdad Monday, claiming at least 13 lives and wounding 53 more.

A booby-trapped car parked near a crowd of construction workers who gather to get a day-long job in the Allawi district in central Baghdad, killing at least four people and wounding some 15 others, an Interior Ministry source told Xinhua on condition of anonymity.

Separately, another attack targeting national police patrol in the southeastern neighborhood of new Baghdad killed two, including a policeman, and wounded four others.

Another car bomb exploded in a crowed market in northeast Baghdad, killing 4 people, 20 others were badly injured.

Later in the Shiite district of Sadr City in northeast Baghdad, a car bomb was detonated near a crowded market, killing three and severely injuring 14 others, the source added.

The toll could rise as ambulances and many civilian cars transported victims to Baghdad hospitals, the source said.

The latest series of blasts came as violence quelled largely for the past year, signaling yet a safer place when U.S. troops start to withdraw.

The toll numbers of March from the Interior Ministry showed that about 252 Iraqis were killed during the month, more or less the same of February, indicating insurgents could still cause fatal attacks despite macro security gains.

According to agreement reached between Washington and Baghdad, U.S. soldiers will also end their combating missions by pulling out of towns and cities this summer. And all 146,000 US troops must leave Iraq before December 31, 2011.

U.S. president Barrack Obama however, has demanded most part of the remaining troops won't leave until Iraqi national election takes place in December for fear of a possible violence surge.

(Xinhua News Agency April 6, 2009)