A toxicology analysis found methanol, a toxic chemical, in the bodies of all 21 teens that collapsed at a bar in East London, South Africa last month, indicating that it was potentially the cause of the shocking deaths. Investigators initially believed the teens may have died in a stampede but now they’re trying to determine if the levels of methanol were high enough to be lethal. Methanol is a toxic form of alcohol used in products not meant for human consumption, such as solvent and pesticide. It is sometimes contained in homemade alcohol. Three people have been arrested in connection with the mass deaths, including the 52-year-old owner of the venue, for allegedly serving alcohol to underage attendees. One 16-year-old attendee told the BBC that people in the bar started to “drop like flies” after gathering to celebrate the end of high-school midterm exams.