Car bombs and shootings killed six people across Iraq on Sunday, authorities said, as clashes between security forces and al-Qaida-linked militants continued west of the capital.

In the ethnically divided city of Kirkuk, three car bombs exploded simultaneously in separate residential neighborhoods, deputy police chief Maj. Gen. Torhan Abdul-Rahman Youssef said. Youssef says four people were killed and 14 wounded.

Arabs, Kurds and Turkomen all stake competing claims to Kirkuk, some 290 kilometers (180 miles) north of the capital, Baghdad.

Near the capital, police and medical officials say gunmen killed a former army officer and his wife in a drive-by shooting in Baghdad's northeastern suburbs.

Also in Baghdad, police found three bodies in different areas. All were killed by what appeared to be close-range gunshots and had their hands and feet tied.

Meanwhile, clashes between security forces and al-Qaida-linked militants continued near a city west of Baghdad, according to local and military officials in western Anbar province.

The officials said that the clashes erupted in the Niamiyah area near Fallujah, seized by insurgents weeks ago. Several Iraqi soldiers were captured by al-Qaida militants during Sunday clashes, he said.

All officials spoke on condition of anonymity because they were not authorized to speak to journalists.

Since late December, members of Iraq's al-Qaida branch — known as the Islamic State of Iraq and the Levant — have held Fallujah along with parts of the nearby city of Ramadi. Government forces and allied tribes have been trying to wrest control back from the militants since.