Gunmen rounded up a Sunni family under death threats for joining U.S.-organized talks with local Shiites, hauling away the men and boys and killing all six Saturday as suspected insurgents expand a campaign of fear against opponents.

U.S. forces, meanwhile, reported airstrikes and raids on what it called Sunni militant bases linked to Al Qaeda in Iraq.

The recent wave of Sunni reprisals appear linked to increasingly high-profile attempts to stir popular momentum against Sunni extremists trying to drive out the Shiite-led government and its American backers.

Among those targeted include a range of fellow Sunnis raising their voices against violence: imams, clan-based vigilantes and activists trying to bridge deep rifts with majority Shiites.

"We are seeing more people beginning to challenge the insurgents," said Marine Brig. Gen. John Allen, who oversees units in the militant heartland west of Baghdad.

The two families gunned down at sunrise Saturday had received death threats for weeks after attending gatherings of Sunni and Shiite leaders, police said.

The first meeting, organized by U.S. military officials on Feb. 13, brought together leaders of prominent clans from both sides, said a military spokesman Maj. Webster M. Wright III.

The clan chiefs held another round on their own about a week later and appointed a joint council "to discuss the terms of reconciliation" around Youssifiyah, a Sunni-dominated area about 12 miles south of Baghdad, said Wright.

At dawn, gunmen stormed the home of two families belonging to the influential Sunni Mashhada tribe, said police 1st Lt. Haider Satar. Two fathers and their four sons were separated from their wives and sisters. They were executed at point-blank range.

In the morgue in nearby Mahmoudiya, Associated Press Television video showed at least two victims had their hands tied bound behind their backs.

Prime Minister Nouri al-Maliki, a Shiite, is under strong pressure from Washington to take a stronger hand against Sunni insurgents and the Shiite militia that forms part of his power base.

In an interview with The Associated Press, he said he will reshuffle his 39-seat Cabinet "either this week or next" and pursue criminal charges against political figures — and even members of parliament — linked to extremists.

"There has been coordination between us and the Multinational Forces ... starting at the beginning of this year ... to determine who should arrested and the reasons behind arresting them," he said.

The prime minister did not say how many Cabinet members would be replaced. But some officials said about nine would lose their jobs, including all six Cabinet members loyal to radical anti-American Shiite cleric Muqtada al-Sadr, who leads the powerful Mahdi Army militia.

U.S. officials had been urging al-Maliki to cut his ties to al-Sadr and form a new alliance of mainstream Shiites, moderate Sunnis and Kurds.

Al-Maliki has won some breathing room in recent days with a notable — but perhaps temporary — drop in bloodshed in Baghdad. It comes as a U.S.-led security crackdown concentrates on areas considered staging grounds for Sunni insurgent car bombs and mortar attacks.

The Mahdi Army also was strong-armed by al-Maliki to pull back. Its suspected death squads once left dozens of Sunni victims around the city — a figure that has fallen off significantly.

For the second consecutive day, just one major explosion rocked the capital. The latest — a roadside bomb — killed three U.S. soldiers on patrol in central Baghdad, the military said.

In western Baghdad, meanwhile, a top adviser to Iraq's Defense Ministry was kidnapped in western Baghdad, said an aide to Adnan al-Dulaimi, a leader of the largest Sunni bloc in parliament.

Lt. Gen. Thamir Sultan hails from Saddam Hussein's tribe and had been mentioned as a possible defense minister when the current government was organized last year. The aide spoke on condition of anonymity because he was not authorized to release the information.

In U.S. raids north of Baghdad, nine suspected insurgents were captured, including two believed to be responsible for recruiting and helping foreign militants in Baghdad, the U.S. military said. The suspects were also accused of harboring Al Qaeda in Iraq leaders, it said, but gave no further details.

U.S. warplanes also struck a suspected car bomb factory in Arab Jabour, south of Baghdad, the military said. Seven suspected insurgents were killed when two precision-guided bombs destroyed the structure where they were hiding, the military said.

In a statement posted on an Islamic militant Web site, a group affiliated with Al Qaeda in Iraq said it has abducted and killed two groups of Iraqi security forces.

The group, calling itself the Islamic State of Iraq, claimed responsibility for the deaths of 14 policemen whose bodies were found Friday in the northeast province of Diyala. It also said it has killed 18 other members of the security force, who were shown in a photograph on the Web site on Friday.

It gave no other details about the 18 captives.