Rescue workers in Syria say President Basher al-Assad’s government dropped barrel bombs containing chlorine gas on a neighborhood in eastern Aleppo on Tuesday. The Syrian Civil Defense organization says 80 people experienced breathing difficulties after helicopters dropped the bombs over the Sukari neighborhood, but there were no known deaths. The group released a video showing wheezing children using oxygen masks in order to breathe. The organization says the Syrian regime is behind two other suspected chlorine gas attacks in August, and the United Nations and Organization for the Prohibition of Chemical Weapons reportedly found last month that government forces were responsible for two chlorine gas attacks in 2014 and 2015. The Syrian government denies using chemical weapons during the country’s civil war.