Millions of Shiite pilgrims thronged the streets of Karbala on Saturday for a religious festival that ended peacefully amid tight security, while at least 15 violent deaths were reported elsewhere in Iraq.

Iraq's Sunni Arab vice president, meanwhile, renewed a call for national reconciliation, asking insurgents and militant groups to join the political process before it's too late.

About 4 million people were in Karbala for the festival observing the birthday of Imam al-Mahdi al-Muntadhar, a ninth century religious leader, said Iraqi armed forces general command spokesman Brig. Qassim al-Musawi.

CountryWatch: Iraq

Thousands of Iraqi army and police troops — backed by air support from the U.S.-led coalition — deployed across the holy city, and a vehicle ban was in place since Wednesday to ward off any suicide bombers. But Iraqi security officials said the festival ended without incident.

The festival attracts pilgrims from across the Arab world, as well as from Iran, Pakistan, Afghanistan, Nepal and India, authorities said.

In most sects of Shia Islam, Mahdi is considered the last "imam," or leader of the Shiite community. The son of the 11th imam, Hasan al-Askari, he is said to have disappeared in the ninth century. But Shiites believe he is still alive and will one day return as a savior of mankind, to create a divine global government based on justice, ending tyranny.

Many people walk to Karbala, 50 miles south of Baghdad, from across the country, and several attacks have occurred in recent days against processions heading to the city.

But Minister of state for national security Sherwan al-Waili said later Saturday that the festival "ended without any incident" and thanked Iraqi and coalition forces that helped provide security.

Hundreds of people have died in suicide bombings and other attacks in Karbala since the 2003 U.S.-led invasion of Iraq. Suspicion has fallen on Sunni Arab extremist groups, including al-Qaida in Iraq, which consider Shiites to be heretics and American collaborators.

Sunni Vice President Tariq al-Hashimi issued his reconciliation plea in a meeting with community leaders from Baghdad's predominantly Sunni Arab Azamiyah district.

Iraqis still have time to avoid sectarian conflict "as the rules of the game have been changed and problems can't be solved only by weapons," he said.

"This is a call for the Iraqi resistance to think thoughtfully and sit around the negotiating table before it's too late," al-Hashimi told about 100 people at the Islamic University. "Differences will devastate Iraq and this division is not to our benefit."

CountryWatch: Iraq

Prime Minister Nouri al-Maliki, who announced he will be visiting Iran on Monday, has launched a 24-point reconciliation plan that he hopes will bridge the religious, ethnic and political divisions that have been tearing Iraq apart.

The plan included an offer of amnesty to member of the Sunni Arab-led insurgency not involved in terrorist activities and calls for disarming primarily Shiite sectarian militias.

But no major Sunni Arab insurgent groups have publicly agreed to join the plan, and many Shiite militias are controlled by legislators themselves.

Violence was reported elsewhere in Iraq, although it was a relatively quiet day.

Two roadside bombs planted four yards from each other exploded as a police foot patrol passed by in the northern city of Kirkuk, killing four people, including one policeman, and wounding 16 others, police Col. Taiyb Taha said.

A parked car bomb also struck a U.S. military convoy in eastern Baghdad, killing at least two passers-by and wounding five, police 1st Lt. Ali Abbas said. The U.S. military said three coalition troops were wounded and were being treated in a military hospital. U.S. soldiers cordoned off the area around a burned-out Humvee.

In Baghdad's central Karradah district, gunmen shot and killed Abdul Karim al-Rubaie, a technician of Iraq's government-run newspaper al-Sabah, and wounded his driver, police said.

Authorities said Iraqi police kept a suicide car bomber from striking a police station near a mosque in northern Baghdad by shooting the driver before he could reach the building. But the explosives in his car still detonated, killing one policeman and wounding 10 civilians, the Interior Ministry said.

In the center of the capital, a bomb exploded as a man planted it by the side of a road, killing the man and wounding another person, and damaging two civilian cars, police Lt. Thair Mahmoud said.

Authorities also found the bullet-riddled bodies of six people dumped in Mahmoudiya, about 20 miles south of Baghdad, Army Capt. Uday Abdul-Ridha said. All had their hands and feet bound and bore signs of torture.

Police also found an unidentified body which was blindfolded and had its hands and feet bound, in the Tigris River in Suwayah, 25 miles south of Baghdad. The body had been shot several times, said Mamoun Ajil al-Rubaie of the morgue in the city of Kut.