A 38-year-old Port Elizabeth man was stabbed to death on Saturday night in Helenvale.
The incident, which happened around 7pm in Pienaar Street, came as a result of the man allegedly physically abusing a little child.
A woman who had witnessed the abuse stabbed the man once in his chest.
Police spokesman warrant officer Alwin Labans confirmed the incident.
"The woman, who cannot be named, was arrested on the scene and will appear in court tomorrow," he said.