Baghdad, Iraq ? Dozens of gunmen wearing Iraqi army uniforms killed a prominent Sunni Arab tribal leader and three of his sons in their beds early Wednesday morning here, according to witnesses and government officials.

The slayings underscore the still-perilous security situation as the country heads toward its third national vote in less than a year. Unsolved murders and the discovery of bound, mutilated bodies have become commonplace amid growing speculation that at least some of the killers are operating from inside the Iraqi security forces.

Witnesses and relatives say Sheik Khadim Sarhid al-Hemaiyem was asleep just before 4 a.m. when his home in the middle-class Hurriya neighborhood was surrounded by gunmen in as many as 10 sport utility vehicles and pickup trucks.

“They surrounded the house from all directions, keeping a few cars on the main road for protection,” said weeping family member Abdel Sattar Jabbar.

Between 30 and 35 gunmen stormed the house, Jabbar said, and killed al-Hemaiyem, 70; his three sons Amir, 35, Waseem, 21 and Allawi, 19; and his son-in-law, identified only as Ali.

“There weren’t any confrontations at all,” Jabbar said. “Then they immediately dispersed, leaving only the dead bodies behind.”

A U.S. Marine from Regimental Combat Team 2 walks to dinner Wednesday at his base in Qaim, Iraq. Qaim is believed to be the principal crossing point for foreign fighters entering Iraq from Syria, according to the military.

The elder al-Hemaiyem was leader of the Batta clan of Iraq’s powerful Dulaimi tribe and a distant fellow tribesman of Defense Minister Saadoun Dulaimi. The Dulaimi name is one of a handful of tribal affiliations that are synonymous with Iraq’s Sunni Arab minority, closely linked with the regime of former president Saddam Hussein and to the ongoing Sunni-led insurgency.

But given the violent, murky landscape of modern-day Iraq, even police officials could only speculate whether the killings were sectarian, tribal or connected to the Dec. 15 parliamentary elections in which al-Hemaiyem’s brother is a candidate.

Meanwhile, the U.S. Army announced the death of an American soldier Wednesday in central Baghdad from a gunshot wound.

The name of the soldier is being withheld pending notification of family. More than 2,100 U.S. military personnel have been killed since the start of the U.S.-led invasion of Iraq in March 2003.