A worried father in Bavaria made a horrifying discovery Sunday morning: the bodies of six teenagers, including his own son and daughter, in a garden shed. Police say there were no signs of violence. The youths, all 18 or 19 years old, were initially thought to have overdosed on an unknown substance, but investigators now suspect that carbon monoxide poisoning caused the deaths, Deutsche Welle reports. Police say the teens had been using a wood-burning stove in the shed. A neighbor told local media that the teenagers had been celebrating the daughter's 18th birthday, the BBC reports.
The AP reports that the owner of the building in a secluded area outside Arnstein, a Bavarian town near Frankfurt, went to the shed after he couldn't reach his children the morning after the party. Police say that while carbon monoxide poisoning is thought to have been the cause, that remains "pure speculation" until autopsy results come in several days from now, MDR reports. (Black market pesticide combined with water was blamed for the deaths of four children in a Texas family earlier this month.)