International alarm is growing over fighting in western Syria, where hundreds of civilians have been reportedly killed amid intense clashes between the country’s new government and loyalists to the regime of former President Bashar al-Assad. Pro-government forces have been accused of killing scores of residents in revenge massacres.

In an update Saturday, the Syrian Observatory for Human Rights, a U.K.-based war monitor that tracks casualties, reported that 1,018 people have been killed in the past two days, including 745 civilians it says were killed in “sectarian massacres” by fighters loyal to the new government.

The reports have not been independently confirmed by ABC News.

The fighting — the worst violence since Assad was toppled three months ago — has gripped areas on Syria’s western coast, in the former Assad heartland around Latakia and Tartus where Assad loyalist gunmen ambushed security forces of the new government on Thursday.

New government security forces, along with thousands of armed pro-government fighters, have poured into the region, clashing with loyalists.

The coastal area is home to the Alawite minority that Assad belonged to and who are now the targets of the reported mass killings.

The Associated Press spoke to residents of Alawite villages and towns, who said gunmen carried out revenge killings of Alawites, mostly men, in the streets. They said some homes were looted and set on fire.

Along with the civilian casualties, the war monitor reported 125 members of the government security forces have been killed along with 148 militants associated with the loyalists.

In addition, electricity and drinking water were largely cut off in nearby areas for the second day in a row, the observatory said. Given the outages and the “deteriorating of the security situation,” bakeries and markets have also closed down, the observatory said.

Syria’s interim leader Ahmed Al-Shara addressed the country on Friday, blaming the violence on people loyal to the old regime and saying they were trying to test the new Syria by stirring up unrest and fragmentation. He called for calm and ordered his security forces not to allow excesses. He said anyone harming civilians would be held accountable.

The UK’s Representative for Syria, Ann Snow called for restraint.

“Deeply worrying developments – restraint & also a clear path to accountability & transitional justice are essential to the peaceful inclusive political transition all Syrians deserve,” she said in a post on X on Friday.