Melbourne boy, 8, was hiding when found unconscious in hot car

It has been revealed the young Melbourne boy found unconscious in a hot car on Monday had been hiding from his mother in the back of the family SUV.

The eight-year-old boy was meant to be in a grade 3 class at St Margaret Mary's Catholic Primary School in Spotswood in Melbourne's west.

While the day started as normal for the family, the boy never made it to school.

The boy’s mother dropped him off at the school gates, along with his brother and sister, but incredibly the eight-year-old managed to sneak back inside the vehicle and hide.

Unaware her son was in the car, the woman continued on for 10 minutes to her workplace at another school in nearby Newport, at Maddox Road.

Some eight hours later, around 3pm Monday, she returned to her car to find her son unresponsive on the back seat.

He remains in a serious condition at the Royal Children’s Hospital where his family holds a vigil at his bedside.

His classmates are also struggling to cope with the tragedy, and both the boy’s school and the public school where his mother works are offering their communities counselling.

"The boy’s mother dropped her children at primary school in the morning however didn’t realise one of the kids had climbed into the rear of the car and hid himself," police said in a statement.

"She has driven to work and parked her car without knowing he was in there."

Fire crews and paramedics were called to the scene and helped the boy out of the vehicle.

He was treated for critical injuries and was transported into the Royal Children's Hospital where he remains in a critical condition Tuesday evening.

Temperatures reached 34C in Melbourne on Monday.

Police said they are treating the incident as an accident.