Downtown Beirut's ordinarily packed streets were largely empty except for security forces as the nation began three days of mourning following the assassination of a prominent anti-Syrian figure.

Independence Day celebrations were canceled as people huddled around televisions to watch the live broadcast Wednesday of dignitaries paying last respects to Pierre Gemayel, a Christian politician whose assassination threatened to push the country's political crisis into wider violence.

Members of the Phalange Party and hundreds of villagers walked past Gemayel's coffin and paid condolences to his father, former President Amin Gemayel, in the family's home in the town of Bikafaya.

Pierre Gemayel, the minister of industry, was assassinated Tuesday. Two cars blocked his vehicle at an intersection in the suburbs of Beirut and a gunman repeatedly shot him through a side window.

One Lebanese person referred to the Gemayels as the Kennedys of Lebanon. Four members of the prominent family have been assassinated over three decades. Pierre Gemayel had just voted for a measure to allow an international tribunal backed by the U.N. to hear a case about the assassination of former Lebanese Prime Minister Rafik Hariri. Syria's involvement in Hariri's assassination has been suspected, but never proven.

Gemayel's killing is the fifth murder of an anti-Syrian figure in Lebanon in two years.

Anti-Syrian factions allied with the Phalange Party expect a huge turnout for Thursday's funeral in central Beirut, intending to show their strength as they wage a power struggle against Hezbollah and other pro-Syrian parties.

The United States denounced the assassination as an act of terrorism. President Bush accused Syria and Iran of trying to undermine Lebanon's government, but stopped short of blaming them for the killing. Syria, too, condemned the assassination and denied any role in it. The Bush administration recently issued a blunt warning to Lebanon's neighbors not to undermine the fledgling democracy there.

Click here to go to FOXNews.com's Mideast Center.

The assassination has spiked already growing tensions in Lebanon. Lebanese politicians struggled to pull the country from the brink, urging calm and unity.

There were calls for revenge among supporters, shouts that were put down by Amin Gemayel, who urged restraint in a call echoed by the Maronite Catholic Church. Nevertheless, there were sporadic cases of violence such as burning tires, wrecking vehicles and attacking offices of rival parties.

Lebanese President Emile Lahoud said Gemayel's murder was part of a "conspiracy" that began with the February 2005 assassination of Hariri.

"I tell the Lebanese that today is the time for them to unite or else all of Lebanon will lose," Lahoud said in a TV address late Tuesday, when he announced the cancellation of Independence Day ceremonies. "We will do the impossible to uncover the criminals because they are against all the Lebanese," Lahoud said.

Prime Minister Fuad Saniora also went on TV to appeal for unity and warn that Lebanon was facing "sedition."

Washington sees Lebanon as a key front in its attempts to isolate Syria and Iran. After the assassination, Bush underlined his support for "the Saniora government and its democracy, and we support the Lebanese people's desire to live in peace."

The draft document Gemayel supported authorized the international court to try suspects in the Hariri murder. A U.N. investigation has implicated several Syrian officials in the murder, which triggered massive protests and forced Syria's ouster from Lebanon. The document now goes to the Lebanese government for final approval.

Six members from Hezbollah and its allies quit Saniora's 24-member Cabinet earlier this month before it gave its backing to the court, sparking the political crisis. The draft of the international tribunal also says that if political assassinations were found linked to Hariri's murder the court will have jurisdiction to try suspects in those attacks as well.

Click here to go to FOXNews.com's Mideast Center.

FOX News' Mike Tobin contributed to this report.