Sarin gas is now thought by many to have been used in the attack in Syria.
Turkey’s health ministry has come to this conclusion after autopsies on some of the victims.
And a UK expert on chemical weapons also says it appears that sarin was used.
Andy Oppenheimer told Sky News: “It’s a very fast-acting agent. Chlorine is different, chlorine is a choking agent that causes horrible symptoms as well. But chlorine generally injures more than it actually kills.
“Sarin will kill, and sarin has been banned as one of the main nerve agents used in warfare.”
Among the many people injured, more than 30 are now being treated in Turkish hospitals and three have died since being transferred there from Syria.