BAGHDAD — Three car bombs in towns south of Baghdad killed at least four people and injured 16 others on Thursday, Iraqi police and health officials said.

The first bombing took place early in the morning in a residential area of the predominantly Shiite town of Mahmoudiya, killing two people and wounding four, police officials said.

Another car bomb went off seconds later at a parking lot near a government agency for electricity, killing one person and wounding three. Mahmoudiya is about 30 kilometers (20 miles) south of the Iraqi capital.

In the southern city of Hillah, a parked car bomb went off in a commercial area, killing one civilian and injuring nine others, a police officer said. The target was unknown to the police. Hillah is 95 kilometers (about 60 miles) south of Baghdad.

Meanwhile, police said two car bombs in a predominately Yazidi town near the northern city of Mosul killed two people late Wednesday.

Yazidis are a Kurdish-speaking sect and religious minority. The bombings in the town of Baashiqa also wounded 12 people, police said.

Health officials at nearby hospitals confirmed the casualty figures. All officials spoke on condition of anonymity because they are not authorized to talk to the media.

Violence has ebbed in Iraq, but insurgent attacks, often aimed at undermining stability in the Shiite-led government, are still frequent.