Turkish forces engaged in Operation Olive Branch against Kurdish militias in the northwest of Syria have used gas, RT reported citing Syrian state media SANA. At least six civilians have been hospitalized.

“Six people have been admitted with symptoms of suffocation as a result of the use of projectiles with poisonous gas by the Turkish regime in the town of Aranda,” SANA quotes the hospital’s director, Joan Mohammed. Medics are working to determine the type of gas used, Mohammed said.

Local journalist Mohammed Hassan tweeted pictures of patients, who were purported to be victims of the attack, wearing breathing masks.

The hospital director said four of the victims were stable and two were in critical condition.

YPG spokesman Birusk Hasaka confirmed to Reuters that Kurds came under what appears to be a chemical attack during Turkey’s offensive on a village, saying that the symptoms of the six people affected are consistent with exposure to a gas poisoning.

Turkey launched Operation Olive Branch on January 20 with a stated goal of securing its borders against Kurdish militia seen as a terrorist organization by Turkey.