The boy's 59-year-old grandfather was driving his family in the car when he swerved into oncoming traffic. He died at the wheel, police in the central state of Thuringia said on Friday morning. His 56-year-old wife - the boy's grandmother was sitting in the passenger set and also died.
His 30-year-old mother was sitting on the back seat with him. Fire fighters cut them from the wreckage but the woman died at the scene of the crash. The boy was taken to hospital by helicopter and on Friday remained there with serious injuries.
The driver of the oncoming car, a 42-year-old man, was injured but not seriously so. He was treated in the same hospital as the young boy.
A police spokesman described the scene on the B176 near Tonna as a “scene of devastation”, and said that it remained unclear why the grandfather had swerved into the other side of the road.
The road was closed for five hours, until 12:30am on Friday, while emergency services cleared the area.