Sydney woman arrested after baby's death

A woman is in police custody after the death of a baby boy in Sydney's southwest.

Officers found the six-month-old unconscious and unresponsive about 4.40pm on Thursday at a house in Oran Park.

They were responding to reports of a concern for welfare at the house.

Paramedics gave the baby boy CPR then rushed him to Campbelltown Hospital, but he could not be revived.

The woman was arrested at the scene, NSW Police said.

She is currently assisting police at Camden Police Station.

A crime scene has been established.