Sectarian clashes linked to the war in neighboring Syria often flare between two impoverished rival neighborhoods in the rundown coastal city.
The Bab Tabbaneh district is largely Sunni Muslim, as are most of the Syrian rebels fighting Assad's rule. Residents of Jabal Mohsen are mostly of Assad's Alawite sect.
Tripoli is overwhelmingly Sunni Muslim but the fighting rarely spreads beyond the two neighborhoods.
Fighting began yesterday after Sunni gunmen shot a man whose brother controls an Alawite militia, sparking gun battles that trapped children in schools and forced traders to flee their shops.