Gunmen have been seen prowling through a Sunni district of the Lebanese city of Tripoli after fighting between factions supporting rival groups in neighbouring Syria’s civil war.
Five people were killed and more than 50 wounded on Thursday night.
Fears are growing the fighting could reignite Lebanon’s own 15-year-long civil conflict.
“The seeds of war exist in Lebanon. If the situation in Syria gets worse, the tensions will flare up and the seeds will sprout,” warned political analyst Younes Awdeh.
Lebanon’s Sunni Muslims tend to back Syria’s rebels while the country’s Shia support Syria’s President Assad whose Alawite sect is an offshoot of Shi’ite Islam.
Along with the sectarian tensions the influx of Syrian refugees is also increasing pressure on the Lebanese people living near the Lebanon-Syria border.
Local estimates claim more than 470,000 Syrians have fled the conflict and are seeking refuge in camps there.