Officials say two drive-by attacks in a western Baghdad suburb have killed three Iraqi soldiers and a policeman as militants seek to undermine government efforts to maintain security.

Two police officers say the first attack took place at dawn Friday, when gunmen in speeding cars opened fire at an army checkpoint just outside the town of Abu Ghraib, killing the three soldiers and wounding five.

They say a joint patrol of Iraqi police and military was targeted in the western Baghdad suburb minutes later. That attack killed the policeman and injured four others. It was not known who the attackers were.

A health official in a nearby hospital confirmed the causalities. All officials spoke on condition of anonymity as they were not authorized to talk to the media.