Police spokesman Hermann-Josef Helmich said police do not yet know who could have committed the killings or what the motive might have been."A witness heard the shots and stopped a police patrol car which was incidentally driving nearby," said another police spokesman, Reinhard Pape.
The bodies were discovered around 2.30am local time and all victims were between 20 and 30 years old, Mr Pape said. He said one of the cars was a small van registered in Duisburg while the other one was a white Volkswagen from Pforzheim in south west Germany. Police started investigating at the crime scene but work was hindered by heavy rain, he said.