A suspected chemical attack in Syria's Eastern Ghouta sparked global outrage Sunday, as state media reported that the last rebel holdouts in the onetime opposition stronghold had agreed to evacuate.
The United Nations Security Council will meet twice on Monday following rival requests by Russian Federation and the United States.
Around 70 people were killed in air strikes, the BBC reported, citing rescue workers and medical staff working on the ground.
The United States, meanwhile, urged the U.N. Security Council to adopt a resolution that would condemn the continuing use of chemical weapons in Syria "in the strongest terms" and establish a new body to determine responsibility for chemical attacks.
US President Donald Trump warned there would be a "big price to pay".
In a series of Tweets early Sunday, Trump said "Many dead, including women and children, in mindless CHEMICAL attack in Syria". Americans are desperately in the quest for legitimate intervention in Syria possibly for another strike against government targets. In admitting to having lost any faith in the moral rectitude of Western governments in matters of war and peace, I don't think that I am alone. Others put the toll even higher.
The White Helmets, who act as first responders in rebel-held areas of Syria, alleged that regime forces had used "poisonous chlorine gas" in the attacks.
The official, who asked to be identified as Dr. Jad, is in touch with local doctors and said one of the affected areas was the residential area of Masaken, where hundreds of civilians reside in underground shelters.
Later Sunday, dozens of buses entered Douma to take detainees released by Jaish al-Islam to government-held territory, according to Syrian state TV. Soon after word of the chemical attack spread, the United States rushed to follow the case seriously and of course this time, too, the Syrian government was in the center of the Washington blame.
"The Assad regime and its backers must be held accountable", she said. They come at seminal junctures in the conflict, when Syrian government forces are on the verge of a significant strategic victory or advance against the alphabet soup of Salafi-jihadi groups that are operating in the country. "That would suit the instincts of a President who only last week said he meant to take all remaining U.S. troops out of Syria".
A year ago, President Trump ordered an airstrike of an air base in Syria following another chemical attack in the rebel held northwestern town of Khan Sheikhoun, where at least 58 people died.
Whitehall sources confirmed the United Kingdom was "not ruling anything out nor in" but acknowledged there were "political issues" around securing parliamentary support for British involvement after MPs voted against strikes following a chemical attack in 2013.
Since February 18, the Syrian government's Ghouta offensive has killed more than 1,600 civilians.
Organization for the Prohibition of Chemical Weapons Director-General Ahmet Uzumcu expressed "grave concern" over the latest use of toxic gas and launched an investigation.
Indeed for neoconservative hawks such as Trump's newly appointed National Security Advisor, John Bolton, the world is America and America is the world, with those who dare resist ripe for attack.