Thousands of people fled the central Syrian city of Homs, the country’s third largest, as insurgents seized two towns on the outskirts Friday, positioning themselves for an assault on a potentially major prize in their march against President Bashar Assad.

The move, reported by pro-government media and an opposition war monitor, was the latest in the stunning advances by opposition fighters over the past week that have so far met little resistance from Assad’s forces. A day earlier, fighterscaptured the central city of Hama, Syria’s fourth largest, after the army said it withdrew to avoid fighting inside the city and spare the lives of civilians.

The insurgents, led by the jihadi Hayat Tahrir al-Sham group, or HTS, have vowed to march to Homs and the capital, Damascus, Assad’s seat of power. Videos circulating online showed a highway jammed with cars full of people fleeing Homs, a city with a large population belonging to Assad’s Alawite sect, seen as his core supporters.

If Assad’s military loses Homs, it could be a crippling blow. The city, parts of which were controlled by insurgents until 2014, stands at an important intersection between Damascus and Syria’s coastal provinces of Latakia and Tartus, where Assad enjoys wide support. Homs province is Syria’s largest in size and borders Lebanon, Iraq and Jordan.