The alleged attack in the town of Douma occurred late Saturday amid a resumed offensive by Syrian government forces after the collapse of a truce with the Army of Islam rebel group.
The reports could not be independently verified.
First responders said they found families suffocated in their homes and shelters, with foam on their mouths. The opposition-linked Syrian Civil Defense were able to document 42 fatalities but were impeded from searching further by strong odors that gave their rescuers difficulties breathing, said Siraj Mahmoud, a spokesman for the group, which is known as the White Helmets.
A joint statement by the Civil Defense and the Syrian American Medical Society, a relief organization, said more than 500 people, mostly women and children, were brought to medical centers with difficulty breathing, foaming at the mouth, and burning of the eyes. It said patients gave off a chlorine-like smell. Some had blue skin, a sign of oxygen deprivation.
It said the symptoms were consistent with chemical exposure. One patient, a woman, had convulsions and pinpoint pupils, suggesting exposure to a nerve agent.
The Syrian Observatory for Human Rights said at least 80 people were killed in Douma on Saturday, including around 40 who died from suffocation. But it said the suffocations were the result of shelters collapsing on people inside.
“Until this minute, no one has been able to find out the kind of agent that was used,” Mahmoud, the White Helmets’ spokesman, in a video statement from Douma.
He said the government was also targeting homes, clinics, and first responder facilities with conventional explosives and barrel bombs. Most of the medical points and ambulances of the town have been put out of service.
Videos posted online by the White Helmets showed victims, including toddlers in diapers, breathing through oxygen masks at makeshift hospitals.
The Syrian government, in a statement posted on the state-run news agency SANA, strongly denied the allegations. It said the claims were “fabrications” by the Army of Islam, calling it a “failed attempt” to impede government advances.
“The army, which is advancing rapidly and with determination, does not need to use any kind of chemical agents,” the statement said.
Syrian government forces resumed their offensive on rebel-held Douma on Friday afternoon after a 10-day truce collapsed over disagreement regarding the evacuation of Army of Islam fighters. Violence resumed days after hundreds of opposition fighters and their relatives left Douma toward rebel-held areas in northern Syria. Douma is the last rebel stronghold in eastern Ghouta.
The alleged gas attack in Douma comes almost exactly a year after a chemical attack in the northern Syrian town of Khan Sheikhoun killed dozens of people. That attack prompted the U.S. to launch several dozen Tomahawk cruise missiles at a Syrian air base. President Donald Trump said the attack was meant to deter further Syrian use of illegal weapons.
U.S. State Department spokeswoman Heather Nauert said that Washington was closely following “disturbing reports” of the alleged chemical weapons attack in Douma.
“These reports, if confirmed, are horrifying and demand an immediate response by the international community,” she said in a statement late Saturday.
The Syrian government and its ally, Russia, denied any involvement in the alleged gas attack.
Douma is in the suburbs of Damascus known as eastern Ghouta. A chemical attack in eastern Ghouta in 2013 that was widely blamed on government forces killed hundreds of people, prompting the U.S. to threaten military action before later backing down.
Syria denies ever using chemical weapons during the seven-year civil war, and says it eliminated its chemical arsenal under a 2013 agreement brokered by the U.S. and Russia after the attack in eastern Ghouta.
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