Officials: 7 Iraqi police killed in attacks - USA TODAY

The attacks before dawn around the city of Fallujah also wounded nine police. They come a week after the leader of al-Qaeda in Iraq announced a deadly campaign to reclaim parts of the country the Sunni insurgency was forced to leave before the U.S. military pulled out last December.

After the attacks Sunday, security forces sealed off all roads leading into Fallujah and imposed a curfew on the city, 40 miles west of Baghdad.

Officials said two explosives-packed cars blew up within a few minutes of each other in Fallujah and the nearby village of Karma as security patrols drove by, killing three policemen. Fifteen minutes later, a gang of gunmen fired on a Karma police station, killing four. The gunmen escaped.

The casualties were confirmed by local hospital officials. All spoke on condition of anonymity because they were not authorized to release the information to reporters.

Fallujah was the site of some of the bloodiest battles of the war in 2004 between U.S. forces and the Sunni insurgency. In 2007, some local tribal leaders in Fallujah and elsewhere in Iraq's Sunni-dominated western Anbar region joined forces with the American troops and forced al-Qaeda to retreat in what was a turning point of the war.

Now, however, al-Qaeda in Iraq is seeking to make a comeback in Anbar and other Sunni areas, launching dozens of deadly attacks in the days since last weekend's statement by Islamic State of Iraq leader Abu Bakr al-Baghdadi that the militant group would push back into its former strongholds .

Al-Qaeda's local wing in Iraq is known as the Islamic State of Iraq, and has for years had a hot-and-cold relationship with the global terror network's leadership.

Both shared the goal of targeting the U.S. military in Iraq and, to an extent, undermining the Shiite government that replaced Saddam Hussein's regime. But al-Qaida leaders Osama bin Laden and Ayman al-Zawahri distanced themselves from the Iraqi militants in 2007 for also killing Iraqi civilians instead of focusing on Western targets.

Generally, al-Qaeda in Iraq does not launch attacks or otherwise operate beyond Iraq's borders. But in early 2012, al-Zawahri urged Iraqi insurgents to support the Sunni-based uprising in neighboring Syria against President Bashar Assad, an Alawite. The sect is a branch of Shiite Islam.

There is evidence of al-Qaeda involvement in the Syrian civil war, especially the appearance of suicide bomb attacks.