BAGHDAD – Gunmen forced their way onto a bus of Shiite pilgrims Monday and shot all 22 men onboard as they traveled through western Iraq’s remote desert on a trip to a holy shrine, security officials said.

The bodies were discovered late Monday, hours after the gunmen stopped the bus at a fake security checkpoint and told the women and children to get off, according to one security official.

The gunmen then drove the bus a few miles off the main highway between Baghdad and the Jordanian border in Iraq’s Sunni-dominated Anbar province. The pilgrims were ordered off the bus and shot one by one, security officials said.

“The terrorists stopped the bus at gunpoint and killed 22 men,” said Maj. Gen. Abdul-Hadi Rizayig, the provincial police chief. He said the highway is protected by the Iraqi army.

Shiite pilgrims have been a favorite target for Sunni insurgents who are trying to revive the sectarian violence that brought Iraqi to the brink of civil war just a few years ago. Monday’s attack comes fewer than four months before U.S. troops — who surged into Iraq in 2007 to stem the religious killings — are scheduled to leave the country.

In Anbar in particular, many insurgents have launched attacks while posing as soldiers or other security guards. On Monday, one of the women who was forced off the bus told officials that four gunmen dressed in military uniforms stopped the bus at a fake checkpoint.

An Iraqi army patrol found the deserted women, weeping and wailing, by the side of the highway. Iraqi soldiers found the deserted bus a short distance away and loaded the women and children back on, and headed back to Karbala.

Two Iraqi security officials and a political leader from the southern Iraqi city of Karbala, where the pilgrims were from, confirmed the shooting details. The pilgrims were on a trip to the Sayyida Zainab shrine in Damascus. Officials gave conflicting accounts as to whether they were headed to Syria or returning.

Violence has dropped dramatically across Iraq, but deadly shootings and bombings still happen nearly every day.