Baby boy dies after Sydney house fire

A six-week-old baby boy has died after being critically burned in a house fire in Sydney's southwest.

NSW Ambulance chief superintendent Mark Gibbs says paramedics were called to the boy's Campbelltown home on Wednesday afternoon.

"The baby had sustained burns to between 80 and 90 per cent of its body and this was a very confronting scene for our paramedics," he said.

"Paramedics provided treatment for the burns, alongside a specialist medical team from the Toll Ambulance Rescue helicopter."

The baby was taken by road to Campbelltown Hospital in a critical condition but died.

A second child was assessed for smoke inhalation, but did not require further treatment.

The death will be investigated and a report sent to the coroner, police said.