Six men were treated for breathing difficulties in the main hospital in Afrin in Syria late Friday after shelling by a Turkish-led offensive on their village, a medical source and a monitor said.
Jiwan Mohammad, the general director of the Afrin hospital, said six men had arrived to the emergency room with "difficulty breathing, coughing, and burning all over the body."
"We have treated them and are observing them now. We kept their clothes for testing," Mohammad told AFP, adding that their symptoms were in line with exposure to toxic agents.
He said they had arrived in civilian cars from Al-Sheikh Hadid, west of the town of Afrin, and had told medics there was shelling on their village.
Turkey and allied Syrian rebels have waged a nearly month-long offensive against the Kurdish People's Protection Units (YPG), which controls the Afrin region.
The assault has seen heavy shelling on border areas between Afrin and Turkey.
An AFP correspondent at the town hospital saw six men wearing oxygen masks and laying under wool blankets, some of them fading in and out of consciouness.
The Syrian Observatory for Human Rights also reported that six people were wounded in bombardment on Al-Sheikh Hadid.
"Shelling from either Turkey or allied factions hit Al-Sheikh Hadid and left six people with enlarged pupils and breathing difficulties," Observatory chief Rami Abdel Rahman told AFP.
Abdel Rahman said he could not confirm whether toxic gases were used.
Ankara has insisted that it is taking all possible measures to protect civilians in its offensive, which it dubbed operation "Olive Branch."
The Observatory says at least 78 civilians have died in the assault.