Boy critical and toddler dead after two separate drowning incidents

A four-year-old has been pulled unconscious from a New South Wales beach, and a toddler has died two hours later in a backyard pool in the same state.

The boy was flown in a critical condition by CareFlight helicopter from Avoca Beach at 6pm.

He was intubated and put into an induced coma for the flight, and is now at Westmead hospital.

His six-year-old sister was also rescued from the water in the same incident.

She was taken to Gosford hospital by road in a stable condition.

CareFlight has praised the surf lifesavers and other responders for their quick actions and vital contributions on the beach tonight.

Two hours later in Sydney's west, paramedics were called after a toddler was pulled from a backyard pool in Greenbank Drive in Werrington Downs.

The two-year-old girl was treated at the scene before being taken to Nepean hospital where she died.

Police are investigating the circumstances and a report is being prepared for the coroner.