The police's Family Violence, Child Protection and Sexual Offences Investigations Unit has been called in to investigate the smoke inhalation injuries of a 17-year-old girl and her four-year-old sister from Kinross, near Secunda.

According to police spokesperson Colonel Benjamin Bhembe, the teenager had an argument with her mother on Wednesday evening and allegedly poured a pot of boiling water over her mother.

The mother sustained serious burn wounds on her right arm and chest and was taken to hospital for further treatment.

When the police tried to enter the house, the teen allegedly held a knife to her sister's throat and threatened to kill her if anyone entered.

It is alleged that she later poured flammable liquid over the furniture and set it alight, before going into the bedroom and hiding her sister in a cupboard.

The fire brigade extinguished the blaze and, after searching the house, found the siblings in the cupboard.

All three family members are in hospital.

Bhembe said a case of arson and attempted murder was under investigation.

He was unable to say what caused the argument between the teen and her mother.