French judicial authorities on Wednesday issued international arrest warrants for Syrian President Bashar Assad, his brother and two army generals for their alleged involvement in war crimes and crimes against humanity, including a 2013 chemical attack on rebel-held Damascus suburbs, lawyers for Syrian victims said.

In addition to President Assad, the arrest warrants were issued for his brother, Maher Assad, the commander of the 4th Armored Division, and two Syrian army generals, Ghassan Abbas and Bassam al-Hassan.

Jeanne Sulzer and Clemence Witt, lawyers at the Paris Bar who represent the plaintiffs, and NGOs behind the complaint, hailed the decision.

“It marks a crucial milestone in the battle against impunity,” Sulzer told The Associated Press on the phone. “It signifies a positive evolution in case law recognizing the grave nature of the crimes committed.”

The Paris prosecutor’s office has not publicly commented on the arrest warrants that remain secret under French law while an investigation is ongoing.

“Legally speaking, this is a procedural act as the investigation into the 2013 attacks in Eastern Ghouta and Douma continues,” Sulzer said. The four individuals named in the arrest warrants “can be arrested and brought to France for questioning by the investigative judges,” she said.

More than 1,000 people were killed and thousands were injured in the August 2013 attacks on Douma and Eastern Ghouta.

The investigation into the two chemical weapons attacks has been conducted under universal jurisdiction in France by investigative judges of the Specialized Unit for Crimes against Humanity and War Crimes of the Paris Judicial Court.