Beirut, Lebanon ? Troops in armored cars deployed to Sunni Muslim neighborhoods in the capital Monday after the shooting death of a young Shiite man, but that failed to prevent renewed friction. Shiite leaders urged the victim’s family to avoid revenge, fearing sectarian violence that could detonate Lebanon’s political crisis.

Lebanese were struggling to contain tensions after Shiites were fired on Sunday as they walked through Sunni and mixed neighborhoods following an anti-government demonstration in downtown Beirut. The attack raised memories of Lebanon’s 1975-1990 civil war, when Beirut was divided by the Green Line between its warring Christian and Muslim districts.

Now Lebanon’s divisions fall along different lines: The government of Prime Minister Fuad Saniora has widespread support among Sunnis, while its opponent, the pro-Syrian Hezbollah, is backed by Shiites. Lebanon’s Christians largely support the government, though a major faction has allied with Hezbollah.

Police said two people were injured late Monday when a group of Shiites, returning home from downtown Beirut, smashed windows of parked cars and stores in a neighborhood near Qasqas, the mainly Sunni area where Sunday’s shooting took place.

Troops fired several warning shots in the air and intervened to prevent the friction from escalating, said security officials, who spoke on condition of anonymity because they were not authorized to speak to the media.

About 300 people also gathered on the highway to Beirut international airport, in an apparent attempt to block the road, but security forces prevented them, the security officials said.

Lebanese supporters of Hezbollah and their allies hold a photo of Ahmed Mahmoud, who was killed during clashes that erupted between groups of Shiites and Sunnis in downtown Beirut, Lebanon. Violent clashes broke out between Shiite and Sunni Muslims on Sunday in the capital, leaving Mahmoud dead from gunshot wounds and dozens of others injured at a time when tensions throughout Lebanon threaten the country's fragile sectarian and political balance.

The body of Ahmed Mahmoud, a 20-year-old Shiite, was brought by ambulance Monday night to downtown Riad Solh Square, where thousands of pro-Hezbollah protesters were camping for the fourth straight night demanding the ouster of Saniora’s U.S-backed government.

The protesters cheered, blared nationalist songs and waved the Lebanese flag as the coffin was placed on a platform in front of the crowd, just a few hundred yards from Saniora’s offices, which were ringed by troops.

Hezbollah’s Al-Manar television station, which aired the event live, called Mahmoud “the martyr of national unity.” Mahmoud’s funeral was scheduled for today.

Mahmoud’s father, Ali, said he initially had thought of revenge but backed down after a visit by envoys of Hezbollah leader Sheik Hassan Nasrallah and his ally, Parliament Speaker and leader of the Shiite Amal Movement Nabih Berri, who said vengeance would only play into the hands of those trying to divide Lebanon.

“They said my son was martyred for the homeland and they don’t want chaos but want all sects to live in harmony, to love each other,” Mahmoud said as he received well-wishers at a funeral hall.

He said he hoped that Saniora, who has been holed up in his office since Friday, will quit. “Then, everything will be fine. We don’t want problems between Sunnis and Shiites, Christians and Druse,” he said.

Ahmed Mahmoud and his brother Hassan were returning home from the protest Sunday and had just turned a corner when heavy gunfire broke out.

“Ali said, ‘Let’s run the other way,'” said Hassan, 22. He said he heard his brother scream and saw him fall, but kept running. An hour later, the family got a call saying Ahmed had been killed by a bullet to the back.