The Lebanese government has authorised the army to take control of the northern city of Tripoli for six months following three days of sectarian clashes.
The decision is aimed at allaying fears that fighting in Lebanon's second largest city was spiralling out of control.
Caretaker prime minister Najib Mikati made the announcement after a high-level security meeting at the presidential palace, saying the army has been empowered to take necessary security measures to keep the peace in Tripoli.
Troops, he added, would carry out patrols and implement arrest warrants issued for fugitives in the city.
Security officials say 12 people have been killed and more than 100 wounded in Tripoli since Saturday, when the latest round of violence erupted. Sectarian clashes linked to the war in neighbouring Syria often flare there between supporters and opponents of Syrian president Bashar Assad.
The fighting is concentrated between two impoverished rival neighbourhoods in the port city. The Bab Tabbaneh district is largely Sunni Muslim, as are most of the Syrian rebels fighting against Assad's rule, while residents of Jabal Mohsen, a neighbourhood perched on a hill, are mostly of Assad's Alawite sect.
The fighting in the past few days has taken on a more ominous turn, spreading to other parts of the city as snipers took up positions on rooftops and gun battles and rocket fire raged out of control.
Fighting began on Saturday 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.
Fighters used rocket-propelled grenades to target their rivals in the crowded neighbourhoods. Schools, universities, banks and other businesses were mostly shuttered today and streets deserted as occasional sounds of gunfire rang out.