Also traveling in the car were the victim's husband and two children, aged seven and nine. They were not injured, but are suffering from severe shock.
The perpetrator fled the scene on the A29 motorway near Oldenburg in the German state of Lower Saxony. He is wanted for murder. The police have assigned 14 officers to the investigation and are working on the assumption that there was no relationship between the killer and the family.
According to the police, a similar incident occurred along the same stretch of the A29 several years ago when a stone crashed through the window of a moving vehicle. That time, there were no injuries as no one was sitting in the passenger seat.