BAGHDAD, Iraq (CNN) -- American soldiers in northern Iraq found a mass grave containing 14 bodies, all believed to be Iraqi security forces or anti-insurgent Iraqis, the U.S. military said Monday.
Iraqis inspect damage to a house caused by an explosion Monday at an Iraqi army checkpoint in Baghdad.
All were shot in the head and had their hands tied behind their backs.
The Americans found the bodies Sunday south of Samarra in Salaheddin province.
The military said it suspects that al Qaeda in Iraq is responsible and that those killed were either Iraqi security forces or members of the Sons of Iraq, the grass-roots, anti-insurgent group backed by the United States.
Salaheddin residents "are standing up to al Qaeda throughout the province because of this and other atrocities committed against innocent people," said Lt. Col. Thomas Hauerwas of the Army's 101st Airborne Division. "Our sympathy and prayers go out to the families of these individuals."
In Baghdad, a pair of car bombings targeting Iraqi security forces killed at least 18 people and wounded dozens Monday, an Iraqi Interior Ministry official said. Watch twisted wreckage of cars after bomb blast »
In the deadliest attack, a parked car exploded near an Iraqi army patrol in central Baghdad, killing 15 people, including one soldier, and wounding 40 others.
Earlier, a suicide car bomb hit an Iraqi National Police checkpoint in eastern Baghdad, killing three officers and wounding nine others -- six police and three civilians, the Interior Ministry said.
The attacks came a day after another car bomb killed four Iraqi civilians and wounded six north of Baghdad in Salaheddin province, the U.S. military said. A child was among the dead.
An American military commander Monday said U.S.-led coalition forces are getting the "upper hand" in their fight against insurgents in Mosul -- a northern Iraqi city with a strong al Qaeda in Iraq presence.
U.S. and Iraqi troops have focused in recent weeks on Mosul, with the Iraqi military gearing up for a major offensive in and around the city.
Troops are making gains and can go anywhere they choose in the city, though some districts are more hostile than others, Army Brig. Gen. Tony Thomas told reporters at the Pentagon, speaking from Baghdad.
"We've seized the initiative, and we have the upper hand," Thomas said. "We think we're disrupting the enemy."
Meanwhile, Jordanian Prince Hassan on Monday expressed outrage at last week's kidnapping of a Chaldean Catholic archbishop in Mosul and the killings of three of the cleric's guards.
"It shocks us greatly to learn of these crimes against those men and women who carry the Abrahamic message of love, peace and brotherhood," said a statement from Hassan, who heads Jordan's Royal Institute for Inter-Faith Studies.
A U.S. military spokesman said Sunday "a great deal of effort" was under way by the Iraqi police and army and the coalition to find Archbishop Paulus Faraj Rahho, who was abducted Friday.
"These holy men must not be made victims of conflict, nor should they pay a price for political quarrels under any circumstances," Hassan said.
Hassan is a member of Jordan's Hashemite royal family, which traces its roots to Islam's Prophet Mohammed. Once in line to succeed his late brother, King Hussein, Hassan was recently awarded the 2008 Niwano Peace Prize for his work on Middle East peace and interfaith dialogue.
Christians are a tiny fraction of Iraq's population. An estimated 1.2 million Christians lived in Iraq before the 2003 U.S. invasion, and about half have remained, according to the U.S. State Department's 2007 Report on International Religious Freedom, citing a top Chaldean official.
Christian religious sites and religious leaders have come under frequent attacks.
Also Monday, Iranian President Mahmoud Ahmadinejad, heading home from Iraq after a two-day visit, again touted the closer relations between Tehran and Baghdad and reiterated his criticism of the United States.
"No one likes them," Ahmadinejad said. "This is the wish of regional nations -- that is the withdrawal of foreigners from this region."
Ahmadinejad's visit was greeted warmly by Iraq's Shiite Muslim leadership, who have had longtime links with Iran that predate Saddam Hussein's toppling. At the same time, many Sunni Muslims in Iraq are opposed to the Iranian regime and have demonstrated against his visit. E-mail to a friend