Clashes between Syrian security forces under the country’s new, Islamist authorities and gunmen loyal to ousted President Bashar Assad in Syria’s western coastal region have killed more than 70 people and left an area outside government control, a war monitor said Friday.

The clashes, which erupted on Thursday and appear coordinated across the coastal region, were a major escalation and a challenge to the new government in Damascus, where the former insurgents now in power have pledged to unite Syria after 14 years of brutal civil war.

Overnight, Damascus sent reinforcements to the coastal cities of Latakia and Tartus, as well as nearby towns and villages — the heartland of Assad’s minority Alawite sect and his longtime base of support, trying to get the situation under control, state media reported.

It was the worst violence since Assad’s was toppled in early December by insurgent groups led by the Islamist Hayat Tahrir al-Sham, or HTS. Since then, there have been some sectarian attacks against minority Alawites, though the new authorities say they won’t allow collective punishment or sectarian vengeance.