A 13-year-old boy has died after being stabbed in the western German city of Witten, police said on Saturday, adding that the child's father has been detained as the suspected perpetrator.
The boy's mother and his 9-year-old sister were seriously injured, a police spokesman told dpa.
He said an argument began inside a residential building before spilling out onto the street, where the boy died despite immediate medical intervention. Several eyewitnesses said they saw the father stabbing the boy.
His sister and mother were treated by emergency doctors at the scene before being transferred to hospital, where they are in critical condition in the intensive care unit.
Neighbours who witnessed the violence were receiving counselling.
The 40-year-old suspect was slightly injured, police said.
Police said no further details about the motive were available. A homicide investigation has been launched.
Officials said the family were German nationals.
The suspect, who was detained some 200 metres from the crime scene, remains in police custody and is expected to be brought before a magistrate. A knife has been secured at the scene.
According to the police, the suspect has not previously come to their attention and there were no indications of any psychological problems.
In a statement published on its website on Saturday afternoon, the town of Witten expressed its deep shock at the violent incident.
Mayor Dirk Leistner said: "The news of this terrible act has shaken us all to the core. The death of a child in particular leaves us speechless. Our thoughts are with the family, the relatives and everyone affected by this incident."
