Unrestrained child seriously injured in crash

Police fear a two-year-old boy found "squashed" in the footwell of a crashed vehicle was not properly restrained.

A little boy was in a car that was T-boned in Roxburgh Park in Melbourne around 8pm on Thursday, with the two-year-old found critically injured underneath a man.

Witness Nathan Rodda said emergency crews didn't know the little boy was in the vehicle until the passenger side door was torn off.

The footwell where the little boy was found. Source: 7News

"A young guy who eventually got the door open, that's when we saw the little boy under the man," he said.

"He was squashed against the door and they got him out. I just froze. I went into shock."

The toddler suffered head injuries and was taken in a critical condition to the Royal Children's Hospital.

His condition has since been downgraded to serious, a hospital spokeswoman said on Friday.

The Roxburgh Park crash scene. Source: 7News

"We know that our most precious cargo needs to be buckled up," Assistant Commissioner Doug Fryer said.

Police believe the child was not properly restrained.

The 30-year-old driver was trapped in the car for half an hour before being taken to the Royal Melbourne Hospital with back and abdominal injuries.

The crash scene. Source: 7News

The other driver Ali Kadik said he was overwhelmed when he found out a child was in the car.

"I got a bit emotional when I found out there was a kid in there because the last thing I need to know is I've taken a little kid's life," he told reporters on Friday.

The 20-year-old suffered cracked ribs and a leg injury in the crash.

"As long as (the toddler) is all good, I'm all good," he said.

The investigation into the crash continues.