In pics: At least 100 killed, 400 injured in Syrian toxic gas attack
More than 320,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests.
Warplanes carried out a suspected toxic gas attack that killed at least 100 people in Syria’s rebel-held north western province of Idlib.
The death toll is likely to rise, according to the Union of Medical Care Organizations.
The Syrian Observatory for Human Rights said those killed in the town of Khan Sheikhun, in Idlib province, had died from the effects of the gas.
The Britain-based monitoring group was unable to confirm the nature of the substance.
Syria’s government officially joined the Chemical Weapons Convention and turned over its chemical arsenal in 2013.
UN-led investigation pointing the finger at the regime for at least three chlorine attacks in 2014 and 2015.
Syrian government denies the use of chemical weapons and has in turn accused rebels of using banned weapons.