(BEIRUT) — Syrian activists, rescuers and medics said Sunday that a poison gas attack on a rebel-held town near the capital has killed at least 40 people, allegations denied by the Syrian government. 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. The Syrian Observatory for Human Rights said at least 80 people were killed in Douma on Saturday, including around 40 who died from suffocation. Opposition-linked first responders, known as the White Helmets, also reported the attack, saying entire families were found suffocated in their homes and shelters.