May said the presence of helicopters and the use of barrel bombs pointed the finger of blame squarely at the government of Syrian President Bashar Assad.
A Syrian soldier films the damage of the Syrian Scientific Research Center which was attacked by US., British and French military strikes.
She is now enjoying global support for her action in Syria and against Moscow over a nerve agent attack on a former Russian spy in Britain.
The 54-year-old general, who left the Syrian army and joined the opposition Free Syrian Army (FSA) after he said he was ordered to carry out a number of chemical attacks on civilians, has maintained contact with officials inside Syria who share intelligence with him.
During a speech to the crowd, Green Party leader Ms. Lucas said: "We will be making the case in Parliament, but this is too big and too important to be determined exclusively by politicians".
"The Syrian regime has reportedly been attempting to hide the evidence by searching evacuees from Douma to ensure samples are not being smuggled from this area", she said.
Ahmet Uzumcu, director-general of the Organization for the Prohibition of Chemical Weapons, said Monday that the organization's team "has not yet deployed to Douma", two days after arriving in Syria.
Fellow People's Voters included Labour Peer Andrew Adonis, who joined the 'Unholy Trinity' for talks with Brussels Brexit negotiator Michel Barnier; Green Party leader Caroline Lucas, who said that uncontrolled, unvetted mass migration "enriches" Britain; and sci-fi actor Patrick Stewart, who said he wanted to obtain USA citizenship purely for the goal of "fighting" Trump.More news: South Korea says officials may visit North Korea ahead of summit
May denied acting at the behest of the U.S.
"We have not done this because President Trump asked us to, we have done it because we believed it was the right thing to do, and we are not alone", May said to cheers.
Chuka Umunna, MP for Lambeth, which had the highest Remain vote in the country, said: "We need more Conservative members of Parliament to be as courageous as Anna and many others who defied the whip and put their country before their party".
Mr Philippe told politicians that France's "riposte" was "proportionate" and sent a strong, clear message to dissuade Syria's Government from using chemical weapons.
The Scottish National Party said it would table a motion for an emergency debate to try to get MPs a vote on whether they backed the action. Furthermore, many are frustrated that the government did not hold a parliamentary vote before launching the strikes, as had occurred previously.
"People had a vote, it was a great vote and they voted with a substantial majority to leave the EU".
Opposition parties say MPs should have been consulted before the United Kingdom joined the USA and France in bombing three Syrian sites, in response to a suspected chemical attack on the town of Douma.
BBC political correspondent Ben Wright said if approved it would be up to the opposition parties to decide if they wanted a vote at the end of the debate.
More than 70 delegations are expected at the April 24-25 donor conference for Syria in Brussels.