A 13-year-old child was killed and 11 people wounded in a gun battle in Lebanon's Tripoli between supporters and opponents of the Syrian president, Bashar al-Assad, a security official said.
Clashes broke out Monday night, as an interview with Assad was being aired on television, and fighting resumed on Tuesday evening.
"Fighting on several fronts in Jabal Mohsen and Bab al-Tabbaneh has killed a 13-year old boy and wounded 11 other people, some of them critically," the official told AFP.
The army was deployed in the area, and shot back at the sources of fire, he added.
The 13-year-old victim was from Jabal Mohsen, a majority Alawite neighbourhood in Tripoli whose residents generally support Assad.
The majority of Bab al-Tebbaneh's residents are Sunni, and support the rebels against Assad in neighbouring Syria.
Both neighbourhoods are extremely poor and marginalised, and lack adequate medical facilities.
Bilal Allush, a 30-year-old vegetable seller from a nearby neighbourhood, told AFP "we all want this violence to end."
"Those people fighting, they are just criminals. Meanwhile, whenever there's a clash, people like me can't work and our families suffer."
Bab al-Tebbaneh is home to Tripoli's main vegetable market, where vendors like Allush can buy in bulk.
"I couldn't go buy vegetables from the market, so I haven't made any money today. My family survives on my daily income. I have four children," he said.
Violence has escalated in Tripoli, Lebanon's second city, since the beginning of Syria's uprising.
Lebanon is deeply divided into pro- and anti-Damascus camps.
Divisions have grown even deeper after the Lebanese Shia movement Hezbollah admitted in May it was sending fighters into Syria to support Assad's troops.
Sunnis have also crossed the border to fight alongside the rebels.
Lebanon was dominated politically and militarily by Damascus for 30 years until 2005.