Iraqi police exchanged fire with a group of gunmen at a checkpoint in a northern Baghdad district on Saturday, killing two civilians and wounding four others, a police source told Xinhua.

"Unknown gunmen opened fire at a police checkpoint in the Shiite neighborhood of Shula in northern Baghdad," Captain Ahmed Abdullah from Baghdad police said.

The police traded fire with the attackers in the crowded area, killing two people and wounding four others, all of them nearby shop owners and pedestrians, he said.

In a separate incident, four people were killed and 18 others wounded, when a car bomb detonated near a restaurant on lunchtime in central Baghdad, an Interior Ministry source told Xinhua.

Also on Saturday, three Iraqi soldiers were killed and eight others wounded when a roadside bomb struck their patrol in southern Baghdad.

Gunmen often attack Iraqi police and security forces, accusing them of being collaborators with U.S. occupation troops.

Source: Xinhua