'Very Traumatic': Son Arrested After Elderly Couple Found Dead In Home

A 46-year-old man is under police guard in hospital after a man and a woman, believed to be his parents, were found dead inside their home in Sydney's south.

Emergency services were called to the home on Tudar Road, Sutherland at 8:30am on Tuesday after receiving a call from a man allegedly threatening self-harm.

Area Commander Jason Box said police believe the 46-year-old man made the call to emergency services himself.

Upon arrival, Box said officers were invited into the house by the man, where they made the gruesome discovery and arrested the 46-year-old.

It's believed the trio lived together inside the home.

Box said police had not previously received any calls for welfare concerns from the premises and said early indications suggest there was no prior mental health history.

Police said there were a "number of injuries" sustained by the elderly couple, who are believed to be the man's 71-year-old mother and 75-year-old father.

Box praised the actions of first responders at the scene, which he described as "very traumatic".

"While they are trained for the worst... walking in and seeing that scenario is quite confronting," he said.

The 46-year-old man remains in hospital where he is being treated for non-life-threatening injuries.

He is expected to be released and taken to a police station later on Tuesday afternoon to be formally charged.

The family's next of kin has been notified.

Investigators are still examining the scene as officers canvas the local area asking anyone who may have seen or heard anything unusual to contact police.