Clashes between pro- and anti-Syrian factions in the Lebanese city of Tripoli killed three people including a Sunni cleric on Friday, jeopardising a fragile truce, a security official said.
The deaths brought to 14 the number of people killed in factional fighting in the Mediterranean port city over the past five days linked to the conflict in neighbouring Syria.
A further 110 people have been wounded, most of them shot by snipers.
A sniper killed Sunni cleric Sheikh Khaled al-Baradei, 28, at dawn, sparking the flare-up between fighters from the pro-Syrian Alawite district of Jabal Mohsen and anti-Damascus Sunni districts, an AFP correspondent reported.
One person died of his wounds in the Sunni Qobbeh area. A third died in the adjacent Sunni Bab al-Tebbaneh district, the security official said.
The militiamen exchanged rocket-propelled grenades and small arms fire in the two neighbourhoods in the east of the city, Lebanon's second largest, sparking several blazes, the correspondent reported.
Families hammered holes through the walls of their apartments to escape to safety down makeshift ladders as the clashes raged.
A journalist and a technician from Sky News Arabia were slightly hurt by stray bullets near the Sunni Bab al-Tebbaneh neighbourhood, another scene of recent clashes on the city's northern outskirts, medical sources said.
Dozens of Sunni militiamen have encircled the Alawite district, with the army separating the rival gunmen, the correspondent said.
The fighting continued until around 8:30 am (0530 GMT) when militiamen on both sides pulled back from the frontline, driving away on motorbikes, and a fragile calm returned.
Six businesses in the city centre were later set ablaze -- four Alawite-owned, one Sunni-owned, and the other a Christian-owned shop selling alcohol, the security official said.
"We were surprised by this battle," said Abu Othman, a gunman from the Sunni side. "They are the ones who opened fire, the Jabal Mohsen people."
Several families displaced by the fighting had returned to the two districts on Thursday to inspect the damage to their homes, as a truce agreed on Wednesday had appeared to take hold.
"I can no longer cope with this situation. In my house I have got three families who have fled the violence," said Ahmed Breiss, who runs a car workshop in Qobbeh.
"We have nothing to do with what's going on in Syria. We want to live in peace," he said.
"We've got barely enough to survive but the militiamen get wages. They're not fighting for any cause, just for their own interests."
Earlier this week, hundreds of soldiers with tanks and military vehicles deployed on the aptly named Syria Street -- which acts both as a dividing line between the rival neighbourhoods and as the frontline when fighting erupts.
A wave of kidnappings preceded the latest round of violence and rattled the already fragile security situation in Lebanon, which lived under three decades of Syrian domination.
Prime Minister Najib Mikati, a native of Tripoli, on Wednesday raised fresh concern over "efforts to drag Lebanon more and more into the conflict in Syria when what is required is for leaders to cooperate... to protect Lebanon from the danger."
The office of the UN High Commissioner for Refugees said on Friday that the mounting insecurity was affecting its efforts to help Syrians fleeing the violence over the border.
"The deteriorating security situation in Lebanon is hampering our work to help refugees fleeing Syria's conflict, though operations are continuing," UNHCR spokesman Adrian Edwards said in Geneva.
"Clashes between rival neighbourhoods in Tripoli continue, affecting the pace of registration from our new centre in the city," he said.
"In the Bekaa valley in east Lebanon, registration of refugees is also affected because of security concerns in the wake of kidnappings of Syrians in the area," he added.
The number of refugees from the 17-month conflict in Syria now tops 200,000, while more than 2.5 million are in need of aid inside the country, according to the UN.
Around 24,500 people have been killed since the uprising erupted in March last year -- with August already the bloodiest month, according to the Syrian Observatory for Human Rights. The UN puts the death toll at more than 17,000.