Scores of people are feared dead in Syria after a possible chemical attack on the rebel-held Douma town in Eastern Ghouta on Saturday, reported CNN.

There is no confirmation of the toll yet. Some rescuers pegged it at 70 and said it was likely to rise, reported BBC. Medical relief organisation Syrian American Medical Society said at least 35 people have died. “We are contacting the UN and the US government and the European governments,” Basel Termanini, the vice president of the US-based organisation, told The Guardian. The Syrian Observatory for Human Rights said 11 people died of suffocation while 70 suffered breathing trouble.

Pro-Opposition Ghouta Media Center and activists groups like the White Helmets and the Douma Coordination Committee said a helicopter dropped a barrel bomb containing sarin, a toxic nerve agent. The Syrian government called the allegations of a chemical attack a “fabrication”.

The United States state department said it was monitoring the situation, adding that Russia should be held responsible if toxic gas had been used. “The regime’s history of using chemical weapons against its own people in not in dispute,” said the US state department. “Russia ultimately bears responsibility for the brutal targeting of countless Syrians with chemical weapons.”

On April 4, 2017, more than 100 civilians were killed in a sarin gas strike in Idlib province, allegedly carried out by the Russia-backed Bashar al-Assad government. Three days later, the US military carried out targeted missile strikes on a Syrian base as a “response” to the suspected chemical attack. The Syrian Army had said the strike had killed six troops and caused “big material losses”. In his statement after the strikes, US President Donald Trump had said the suspected gas attack had “cross a lot of lines” for him.