With UN weapons inspectors still refused access into Syria by the Assad regime, it is not yet clear what actually caused so many deaths in Damascus.
Most experts say it looks like some kind of chemical attack took place, but there is disagreement whether a nerve agent like Sarin is to blame.
The chemical evidence will remain for only another 12 to 24 hours, which means time to establish the facts of what happened is running out, as Paul Davies reports.
Warning: This report contains graphic images
Britain has directly accused the Assad regime of gassing hundreds of Syrian civilians amid warnings only 48 hours remain to find proof.
New videos show the eyewitness accounts of four men who witnessed an alleged chemical attack on Zamalka, a suburb of Damascus.
These are the images of the remains of rockets which, according to the men stood by them, delivered poisonous gas to a suburb of Damascus.