A Palmerston North family is heartbroken over losing their "miracle baby" after he fell through the roof of a school building, fracturing his skull.

Eight-year-old Justin Reid was playing with his big brother Lucas and several friends on Saturday at Cloverlea School when he gained access to the roof of a school building.

His aunt Kim Murphy said it wasn't clear how Justin ended up on the roof.

But being little, the family assumed he had been given a boost by one of the other kids.

"Apparently some other teenagers were on the roof too, so we assumed he was coaxed up there."

Shortly after 4pm, Justin fell through a Perspex strip in the corrugated iron roof and landed on his head.

Realising his little brother was unconscious, Lucas, 10, called for help. St John ambulance crews rushed to the scene within 30 minutes.

"He was brought to A&E straight away and they ran some scans," Murphy told the Herald.

"It was clear pretty quickly how serious the injuries were."

The little boy, who was described by his aunty as a "loving, witty" kid, was put on life support at Palmerston North Hospital's intensive care unit.

With a fractured scull and severe brain injuries, the family could only hope he would pull through.

But when he was pulled out of sedation yesterday to enable doctors to see how his brain was reacting to the trauma, the family was told he was brain dead. They made the decision to turn off life support yesterday afternoon.

Justin with his niece Azariah, the daughter of his eldest brother Josh. PHOTO / Supplied

His aunt said the circumstances around the fall seemed out of character for Justin, who was afraid of heights.

Justin and Lucas often went to Cloverlea to play on their scooters on a bike track at the school with other children. The boy was full of life, she said, but wasn't exactly a dare devil.

"He was just a regular 8-year-old boy."

Murphy said Justin was the youngest of five.

His oldest brother Josh was 19, who had a young daughter, Azariah, who Justin was very fond of.

He loved Black Ops "even though he shouldn't have been playing", and he loved cars.

Justin was very close to his four siblings, and loved his mum, Murphy's sister Angela.

His aunty said Justin's favourite colour was green and he lit up when he was around music.

"He was very cheeky, very cute and very loved."

Justin's mum Angela Reid is separated from his father, Tony, but the pair are still very amicable.

Angela Reid called Justin, 8, her "miracle child" as she fell pregnant with him after having her tubes tied. Photo / Supplied