'My baby': Mum hysterical as twin son dies in hot car

A one-year-old has been found dead at a home in Chester Hill. Image / News Corp Australia

Investigations are continuing into the death of a baby boy after he was left inside a sweltering car yesterday afternoon in Sydney's west.

Emergency services rushed to the Chester Hill home on Ohagan St around 3.30pm to reports the 22-month-old boy was unconscious inside in the locked car.

He was pulled from the car and paramedics frantically worked to revive the child but he was unable to be saved.

He was pronounced dead at the scene.

It's understood the boy was a twin and his mother had briefly left him in the care of other family members.

Police had just started setting up their crime scene when the mother returned home to hear the horrific news, running down the street and screaming "my baby".

The distraught mother was being assisted by police when an older woman, believed to be the boy's grandmother, was wheeled out of the Chester Hill home on an ambulance stretcher.

It's understood the grandmother was being treated for shock and the baby boy had been in her care when he was accidentally left in the car.

Temperatures in Chester Hill exceeded 30C yesterday.

The death is still the subject of a police investigation, with police officers from Bankstown Police Area Command establishing a crime scene and continuing investigations.

The cause of death yet to be determined, and a report will be prepared for the Coroner.

Police have reminded the public that information will be treated in "strict confidence", and the public is also urged not to report crime via NSW Police social media pages.

Police were told the child was located inside a car at the front of the residence by family members, after concerns were raised he could not be found inside the home.