A sniper killed a Shiite pilgrim on a Baghdad bridge Monday while another was killed and a dozen injured in other attacks as tens of thousands of faithful made their way to the southern city of Karbala for a major religious commemoration.

Later Monday, in what could have been a retaliatory strike, a homicide bomber killed 10 people and wounded 11 when he blew himself up after evening prayers in a Sunni mosque in Falluja, ppolice and hospital sources said.

The violence came as the U.S. military reported the deaths of four service members.

Two Marines were died in western Anbar province — one on Saturday and the other Sunday — while two soldiers were killed Sunday in a firefight in Samarra that saw a dozen insurgents killed, the military said.

Some 30 masked insurgents attacked a U.S. outpost Sunday, triggering the gunbattles that ended when a U.S. jet bombed a house where gunmen had taken refuge. In addition to the dead, 14 insurgents were captured and U.S. forces seized four assault rifles, one sniper rifle and one machine gun, the military said.

Iraqi officials said eight people were killed. Police and hospital officials identified the dead as Mohammed Abdul-Wahab, his mother, wife and five of his young children.

U.S. military spokesman Lt. Col. Michael Donnelly told The Associated Press that he only had reports of two civilian casualties, a male and a female who were in a taxi moving through the area during the initial firefight.

"Any civilian casualties are truly regrettable, but it is important to understand that our forces are there to secure the people of Samarra and bring them peace, not bring them harm like the insurgents did," Donnelly said.

In the same province, the governor, Hamad Hamoud Shightay, escaped a roadside bomb attack on his convoy Monday, his office said.

Two nearly simultaneous explosions went off as the governor's convoy was on the way to the local university. A car was seriously damaged and a bodyguard injured, but the governor was unharmed, his spokesman Maj. Muthanna al-Qaisi said. Two southern provincial governors were assassinated earlier this month.

In order to protect the Shiite pilgrims on their way to Karbala, Iraqi security forces have mounted a major security operation. Sunni religious extremists, including Al Qaeda in Iraq, have launched massive and deadly attacks against pilgrims during Shiite celebrations in the past.

Despite the security measures, one pilgrim was shot on Baghdad's Jadiriyah bridge and gunmen hiding in an orchard south of the capital opened fire on another group, killing one and injuring three others.

Nine other pilgrims were injured in two other assaults in Baghdad, and police prevented another attack, defusing two roadside bombs planted along the route to Karbala in Musayyib, about 40 miles south of Baghdad, officials said.

More than a million Shiites from throughout the world were expected to converge on the Shiite holy city for the celebrations, which reach their high point late Tuesday and early Wednesday. The Shabaniyah festival marks the birth of Mohammed al-Mahdi, the 12th and last Shiite imam who disappeared in the 9th century.

In Fallujah, Police said the bomber had entered the office of the imam, Abdul Sattar al-Jumaili, his son and a group of worshippers had been meeting.

Security concerns are running high, in part because of the political deadlock that has paralyzed the government only weeks before U.S. Ambassador Ryan Crocker and Gen. David Petraeus report to Congress on progress here since the arrival of an additional 30,000 U.S. troops.

Key Democrats including Sen. Hillary Clinton have called for Prime Minister Nouri al-Maliki to be replaced because his Shiite-dominated government has been unable to forge national unity.

In a late meeting Sunday, top government leaders said they had found common ground on some main issues standing in the way of reconciliation.

But the meeting, attended by Crocker, failed to win a pledge by the main Sunni bloc, the Iraqi Accordance Front, to return to the government. This month's Sunni decision to bolt al-Maliki's government plunged the country into a political crisis.

The meeting brought al-Maliki together with fellow Shiite Vice President Adil Abdul-Mahdi, Sunni Arab Vice President Tariq al-Hashemi, the head of the northern autonomous Kurdish region Massoud Barzani and President Jalal Talabani, who is also a Kurd.

They said they agreed on some issues that the U.S. has set as benchmarks for progress, among them holding provincial elections, releasing prisoners held without charge and changing the law preventing many former members of Saddam Hussein's Baath Party from holding government jobs and elected office.

But no details were released and committees must hash out final versions of legislation to be presented to parliament. Iraqi officials have announced similar deals in the past, only to have them fall apart.

Khalaf Al-Ilayan, chairman of the National Dialogue Council, which is part of the Accordance Front, scoffed at the declaration, saying that "no real or practical solution will come out of this."

"Our stance is that this meeting represents a new phase of procrastination, and does not honestly aim at quickly solving the problems," he told The AP in Amman, Jordan.

Nevertheless, White House spokeswoman Emily Lawrimore called the resolution an "important agreement."

It is "an important symbol of their commitment to work together for the benefit of all Iraqis," she said in an e-mail statement.

Before the meeting, al-Maliki said Clinton, of New York, and other Democrats who have called for his ouster should "come to their senses" and stop treating Iraq like "one of their villages."

Clinton and Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, have called for al-Maliki to be replaced.

Al-Maliki also demanded an apology from France, after Foreign Minister Bernard Kouchner was quoted by Newsweek magazine as saying the Iraqi government was "not functioning" and that al-Maliki has "got to be replaced."

In an interview Monday with RTL radio, Kouchner said, "I think that (al-Maliki) misunderstood, or that I was not clear enough that I was referring to comments I heard from Iraqis I talked to" during his visit here this month.

"If the prime minister, Mr. al-Maliki, wants me to apologize for having interfered so directly in Iraqi affairs, I'll do it willingly," Kouchner was quoted as saying.