The toll in renewed fighting in the northern Lebanese city of Tripoli rose to four on Friday, as Syria-linked clashes flared again, a security source told AFP.
In the east of the country, meanwhile, two shepherds -- one Lebanese, one Syrian -- were killed by fire from across the border in Syria.
The deaths in Tripoli were the latest in a round of fighting between gunmen in the Sunni district of Bab el-Tebbaneh and fighters in the Alawite Jabal Mohsen neighbourhood.
The source said two people was killed in Bab el-Tebbaneh and a third in Jabal Mohsen overnight, as gunmen fired from both sides.
The fourth died in Jabal Mohsen of wounds sustained two days earlier.
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Tensions between the two districts go back decades, but have been exacerbated by the conflict in Syria, where President Bashar al-Assad, an Alawite, is battling a Sunni-led uprising.
The latest clashes in Tripoli began last Thursday, and the most recent deaths bring the toll in just over a week to 16, the security source said.
Lebanon's army has deployed in the city in a bid to calm the tensions, but has also come under fire.
Overnight, an explosive device detonated as the army patrolled in the city, wounding one soldier, the security source said.
In Lebanon's eastern Bekaa region, meanwhile, a security source said two shepherds were killed along the border with Syria.
"Syrian troops opened fire on them," the source said, speculating that the soldiers may have suspected them of trying to cross the border.
Fire from Syria's conflict regularly spills over into Lebanon, with many border areas subject to shelling and even air raids by Syrian regime warplanes.