<Li> Operation Martyr Muath </Li> <Li> Foreign rebel fighters </Li> <P> The Khan Shaykhun chemical attack took place on 4 April 2017 on the town of Khan Shaykhun in the Idlib Governorate of Syria . At the time of the attack, the town was under the control of Tahrir al - Sham, previously known as the al - Nusra Front . </P> <P> The town was reported to have been struck by an airstrike by government forces followed by massive civilian chemical poisoning . The release of the toxic gas, which included sarin, or a similar substance, killed at least 74 people and injured more than 557, according to the Idlib health authority . The attack was the deadliest use of chemical weapons in the Syrian civil war since the Ghouta chemical attack in 2013 . </P>

When did the chemical attack in syria happen 2017