A monitoring group reported on Saturday that three days of clashes between forces from Syria’s new government and fighters loyal to ousted dictator Bashar al-Assad have resulted in the deaths of more than 300 civilians and numerous combatants from both sides.

According to the British-based Syrian Observatory for Human Rights, which has been monitoring the Syrian conflict since 2011, the clashes have claimed the lives of over 400 people in total across two Syrian coastal provinces. The majority of the civilian casualties were attributed to fighters affiliated with the government.

In response to allegations of civilian killings, officials from the Information Ministry rejected “undocumented allegations accusing government forces of committing violations.” However, they also stated that the government is committed to conducting comprehensive investigations and holding those found responsible for harming civilians accountable.

The government confirmed that its forces operate according to strict standards respecting international humanitarian law and emphasized its commitment to protecting civilians during operations.

The ongoing unrest marks the bloodiest outbreak of violence since the ousting of the Assad regime in early December and poses a significant challenge to the authority of the new government. It has raised concerns of additional sectarian conflict in Syria, where tensions were already heightened due to the ongoing civil war.

The clashes began on Thursday when Assad loyalists killed 16 government security personnel in Latakia province, marking the deadliest attack on Syria’s new security forces thus far, according to government officials and the Observatory.

Violence swiftly spread across Latakia and Tartus provinces, which have been long-standing strongholds of Assad along the Mediterranean coast and are home to the country’s minority Alawite population. Armed remnants of the ousted regime are believed to be scattered across the two provinces, posing a challenge to the new government’s authority and efforts to unite the fractured nation.

In response to the initial attack on Thursday, the government deployed thousands of security forces and soldiers from other parts of the country to the rebels in the coastal region. Their objective was to regain control over several towns and villages that armed gunmen had effectively seized overnight.

The government aimed to present the clashes as a legitimate authority combating remnants of a brutal regime.

Government forces utilized helicopters equipped with machine guns in the mountainside of the coastal region, as reported by a government official on the coast who wished to remain anonymous. Helicopters were deployed to areas where armed Assad loyalists were stationed.

A video verified by The New York Times, filmed along the coast west of Latakia airport, appears to show government fighters dropping improvised bombs from a helicopter. A government spokesperson in Latakia did not respond to a request for comment regarding the video.

Contributions to reporting were made by Christina Goldbaum and Muhammad Haj Kadour.