Six teenagers who were found dead in an allotment shed in the German town of Arnstein at the weekend died of carbon monoxide poisoning, police said Tuesday. The women and men found dead were aged between 18 and 19 and had met up Saturday evening - apparently for a party - in the shed on a remote plot of land in the Lower Franconia region of Bavaria. The bodies were found on Sunday after the owner of the plot, whose son and daughter were among the dead, went to check on the group. He had started to worry after not hearing from them by morning. Officials have not confirmed whether a wood-fired heater that the youth had been using to heat the shed is linked to the deaths. "The cause of the toxic gas leak is still the subject of a criminal investigation," police and prosecutors said in a joint statement released Tuesday. Friends and relatives of the victims attended an ecumenical service at a local church late Monday. Arnstein has a population of 8,000.