GENEVA (Reuters) – War crimes were likely committed by interim government forces as well as by fighters loyal to Syria’s former rulers during sectarian violence that culminated in a series of massacres in March, UN investigators said on Thursday.

Some 1,400 people, mainly civilians, were reported killed during the violence in coastal areas that primarily targeted Alawites, and reports of violations such as abductions continue, according to a report by the UN Syria Commission of Inquiry.

“The scale and brutality of the violence documented in our report is deeply disturbing,” said Paulo Sergio Pinheiro, Chair of the Independent International Commission of Inquiry on the Syrian Arab Republic, in a statement released with the report.

Murder, torture and inhumane acts related to the treatment of the dead were documented by the UN team, which based its 56-page report on more than 200 interviews with victims and witnesses as well as visits to three mass grave sites.

Most victims were Alawite men aged between 20-50, but women, and children as young as one, were also killed, the report said. Sometimes the killers, who went door to door looking for members of former President Bashar al-Assad’s minority Alawite sect, filmed the executions themselves, it said.

Perpetrators were members of the interim government forces as well as private individuals operating or in proximity to them. Fighters loyal to the ousted Assad government also committed violations, it said.

The report is not all-encompassing, since incidents in Homs, Latakia and Tartus are still being investigated by the commission, set up by the UN Human Rights Council in 2011.

The incidents along the coast were the worst violence to hit Syria since the fall of Mr. Assad last year, prompting the interim government to appoint a fact-finding committee.

“The Syrian Arab Republic values these efforts and reaffirms its commitment to incorporating the recommendations into the ongoing process of institution-building and the consolidation of the rule of law in the new Syria,” Foreign Minister Asaad Hassan al-Shibani said in a letter responding to the report, which it said aligned with its own findings.

There was no immediate public comment from former Syrian officials, many of whom have left the country.

U.S. Special Envoy for Syria Tom Barrack welcomed the report and said it was a “serious step” towards assessing responsibility for violations. The administration of President Donald Trump is gradually lifting Syria sanctions dating back to Mr. Assad’s rule.

A Reuters investigation last month found nearly 1,500 Syrian Alawites had been killed and identified a chain of command from the attackers directly to men who serve alongside Syria’s new leaders.

New Syrian President Ahmed al-Sharaa has previously denounced the violence as a threat to his mission to unite the country and promised to punish those responsible.

The commission acknowledged in its report the commitment of Syria’s interim authorities to identify those responsible but said the scale of the violence warranted further steps.

“Guarantees of non-repetition of the violations should be at the heart of Syria’s transition,” the report said.