Emergency services rushed to Maddox Road in the inner Melbourne suburb of Newport after one of the boy's parents found him inside his parents' black Kia Carnival minivan at 2.45pm.
A child has been rushed to hospital with critical injuries after being found in a vehicle. (9NEWS) A child was rushed to hospital just after 2.45pm.
He was in cardiac arrest and "not breathing" according to early reports - and was taken to hospital immediately.
The mother had dropped the boy and his siblings off at St Margaret Mary's Catholic Primary School in Melbourne yesterday morning, police said.
The boy was unresponsive by the time emergency crews reached him and remains in a critical condition at the Royal Children's Hospital.
Same-Sex bill could override anti-discrimination laws
Australia has edged closer to legalising same-sex marriage with a diverse group of cross-party senators backing a Liberal senator's bill to change the law.
The mother then drove to work in Maddox Road, Newport, unaware that he was in the vehicle.
It has been confirmed the boy was the son of a staff member at the nearby Newport Gardens Primary School.
Police said: "She has driven to work and parked her vehicle without knowing he was in there".
Homicide Squad detectives were brought in "as per protocol" and were "assisting only at this time", police said in a statement.
"Support will be made available for any staff, students and families that need it", Mr McGlade said, asking for privacy for those involved.
Justice League Cast Hits the Red Carpet in Premiere Live Stream Video
While he ponders his own future as the Dark Knight, the actor does see a timeliness in Justice League's arrival now. Even if it's unclear when Justice League Part 2 will come out, it's still likely that it will, eventually be made.
An eight-year-old boy is fighting for life after being trapped in a auto during sweltering temperatures in Melbourne on Monday afternoon.
"It's just a very sad situation, " one said.
"Get your children out of the vehicle, do not leave them there, whatever inconvenience that involves, it's a price worth paying", she said.
Bill El-Hawli, who has lived on Maddox Road for 35 years, found out about it while watching the evening news.
McLaren, Pirelli cancel Brazil tyre test due to security concerns
Mercedes has won both of this year's championships for the fourth year in a row with Lewis Hamilton arriving in Brazil as a four-times world champion.