Lebanon’s army is marching into the northern coastal city of Tripoli today after clashes between Sunnis and Alawites in the city left at least 15 people killed and scores of others wounded.

Lebanese Prime Minister Najib Mikati held a meeting at his home in Tripoli with top military officials, ordering “decisive measures” to be taken to end the fighting, which is flaring up as a result of the incipient civil war in neighboring Syria.

Northern Lebanon has seen a number of refugees fleeing from the Syrian fighting, as well as rebel forces who have crossed over in an attempt to use the area as a staging ground. This has riled up already tense relations between Lebanon’s Sunnis and Shi’ites, who have been split over the Hezbollah-led government for quite some time.

This is the largest single clash in Lebanon, but other incidents have seen Shi’ites kidnapped and Sunni clerics announcing the creation of a “Lebanese Free Army” modeled after the Syria rebels in response to two killings.