Residents of Bhekuzulu township in Vryheid, northern KwaZulu-Natal, are still reeling from shock after a man attacked his in-laws before turning the gun on himself.
The man, Vusi Magwaza, 38, allegedly became angry when he could not find his wife at his mother-in-law's home on Friday.
He shot and killed his sister- in-law and wounded his mother-in law.
The sister- in-law, Makhosi Masondo, 32, was shot five times and died instantly. The mother-in-law, Roda Sithole, 56, was shot once and is in a stable condition at a local hospital.
Magwaza then turned the gun on himself.
It is alleged that the argument that sparked the shooting concerned making contributions to a relative's funeral.
Magwaza allegedly wanted his wife to give him her bank card so he could withdraw money to contribute to the funeral, but she refused.
His wife, Thobile, left for her mother's home, claiming her husband wanted to kill her.
Magwaza's mother, Lenah, 62, yesterday said on the day of the incident, her son looked like someone possessed.
She said when he arrived home with his wife, they were talking but seemed tense.
"I don't know what happened except that after their argument she ran and he followed her," said Magwaza.
"He looked so crazy I couldn't believe that he was my son."
She said she heard about the killings a few hours later.