BEIRUT The tensions between the two neighborhoods were building for days in the northern Lebanese city of Tripoli. On one side live Sunni Muslims who hate the Syrian regime. On the hill above are members of the Alawite sect, Bashar Assad's strongest backers.

Overnight Friday, tempers exploded. For hours, gunmen in the two districts traded automatic weapons fire and volleys of rocket-propelled grenades across the avenue that divides them, ironically named Syria Street.

By the time a shaky truce was reached Saturday, two people were dead - one from each side - and 12 people wounded, half of them soldiers trying to stop the clashes.

The fighting underscored how the bloodshed in Syria, where Assad's regime is cracking down on an 11-month-old uprising against his rule, is enflaming emotions in its tiny neighbor Lebanon. The already deep divisions between Lebanese are being strained, and many fear Syria's chaos will bleed over across the border.

Lebanon split over Syria

Lebanon is sharply split along sectarian lines, with 18 religious sects. But it also has a fragile political faultline precisely over the issue of Syria.

There is an array of diehard pro-Syrian Lebanese parties and politicians, as well as support for the regime on the street level. There is an equally deep hatred of Assad among other Lebanese who fear Damascus is still calling the shots here. The two sides are the legacy of, and backlash against, Syria's virtual rule over Lebanon from 1976 to 2005 and its continued influence since.

Tempers between the two sides are high enough. But Syria opponents worry the regime may intentionally cause trouble.

"The Syrian regime holds a lot of cards in Lebanon, and the biggest fear is that as the Assad regime gets more desperate, it would decide to use them to create regional chaos," anti-Syrian politician Mustafa Alloush said.

Among those cards is Hezbollah, the Syrian and Iranian-backed Shiite militant group with an arsenal of weapons more powerful than that of the Lebanese army.

Already, any talk about Syria is potential cause for a fight.

Northern Lebanon, in particular, is a potential powder keg.

It has a strong Sunni Muslim population, sympathetic to its sectarian brethren who have been the backbone of the Syrian uprising. But it also has pockets of Alawites, the Shiite offshoot that makes up the majority of the Syrian regime's leadership and to which Assad himself belongs.

The weekend clashes were between the mainly Sunni Bab Tabbaneh neighborhood and the adjacent Alawite-majority Jabal Mohsen, on a hill overlooking its rival.

Accusations of complicity

The tensions come at a time when anti-Syrian parties in Lebanon, which once ran the government, are weakened. They were replaced in 2010 by a government dominated by Hezbollah and pro-Syrian allies. Prime Minister Najib Mikati, a personal friend of Assad, says he isn't taking sides in the crisis, adopting a policy of "disassociation."

Still, opponents accuse the government of complicity with Damascus.

Lebanon voted against suspending Syria from the Arab League in November and was the only member state that did not endorse a League plan calling on Assad to transfer powers to his vice president.

"The Lebanese government is cooperating with the Syrian regime; they are only using this policy of disassociation as a cover," Alloush said.

A longtime Syrian military presence in Lebanon ended after massive 2005 protests sparked by the killing of former Lebanese Prime Minister Rafik Hariri in a car bombing. Many Lebanese accuse Syria of involvement in the assassination, a charge Damascus denies.