On the day of the attack fighting occurred between Syrian Army soldiers and opposition fighters in Ashrafiyat Sahnaya, as part of the Rif Dimashq offensive (March–August 2013).

[1]: 17 Around 20:00 an object filled with sarin was thrown at a group of five Syrian Army soldiers.

The five soldiers were immediately taken to a field medical point where they were treated with injections, eye droplets and oxygen.

They were then transported to Martyr Yusuf Al Azmah Military Hospital for emergency care, where medical personnel took blood samples.

[1]: 17–18, 71–78 The United Nations Mission to Investigate Alleged Uses of Chemical Weapons in the Syrian Arab Republic collected evidence "that suggests that chemical weapons were used in Ashrafia Sahnaya" "on a small scale against soldiers", but said they lacked primary information on the delivery system.