Seven people, including a three-year-old boy, have been killed since Saturday in the northern Lebanese city of Tripoli, medical and security sources said.
The victims are the latest casualties of violence fuelled by sectarian tensions over neighbouring Syria's civil war.
Tripoli, 30 km (20 miles) from the Syrian border, has been sharply divided on the basis of community for decades.
The Lebanese army used "rockets" for the first time to quell the fighting between rival neighbourhoods, one security source said, without specifying which weapons were used. Normally, soldiers use assault rifles to target snipers.
The sources said three people killed by snipers were from the Bab Al Tabbaneh district, whose residents overwhelmingly support the rebels battling Syrian President Bashar Al Assad.
Three others killed were from the Alawite neighbourhood of Jebel Mohsen, which supports fellow Alawite Assad. Two of them were killed by snipers and a third was shot during a street clash.
A boy aged three from the nearby neighbourhood of Qoubbe died from wounds he sustained as a result of the fighting.
Sniper attacks are common along Syria Street, which divides the rival neighbourhoods and adjacent roads.
Sources said 53 people had also been wounded in the past 48 hours in related clashes, including four soldiers. The army has been deployed across the city for months in an effort to quell the violence.
Sectarian clashes in Tripoli killed more than 100 people in 2013. Dozens of people died in gun battles, and twin car bombs at Sunni Muslim mosques killed 42 people in August.
Follow Emirates 24|7 on Google News.