Police confirmed a short time ago that 49-year-old driver had been charged with four counts of dangerous driving cause serious injury.

He will appear in Melbourne Magistrates Court via video link.

Nine children aged 5-11 sustained traumatic or serious injuries in the collision at about 3.40pm on Tuesday.

Specialist doctors have been called in to perform emergency surgeries at the Royal Children’s Hospital.

A Code Brown, an emergency response for hospitals anticipating mass causalities, was declared after the accident and ended at about 8pm.

Students from Exford Primary School were making their way home when a truck hit the school bus from behind.

Children were trapped inside the bus before witnesses and emergency workers pulled them from the wreckage and transported them to hospital.

Parents faced an anxious wait overnight before finally being reunited with their children early Wednesday morning.

Seven children are still in a serious condition, with four undergoing surgery overnight and another two going into theatre on Wednesday. Two have been discharged.

Bernadette McDonald, chief executive at Melbourne’s Royal Children’s Hospital, said so far one child had undergone a complete limb amputation.

“The children have suffered multiple and traumatic injuries including partial and complete amputations of arms, multiple crushed limb injuries, severe lacerations to head and body, head injuries and glass shard injuries,” McDonald told reporters on Wednesday.

“Three patients are currently receiving spinal support and being monitored, carefully, in terms of spinal injuries.”

Multiple surgeons are in attendance including the hospital’s own doctors and vascular and specialist microplastic surgeons from Royal Melbourne Hospital.

“You would understand with these sorts of injuries very small vessels need to be repaired and reattached,” McDonald said.

The first child was in surgery after 4.30pm on Tuesday, an hour after the accident.

Many children will be required to undergo multiple surgeries in the coming days and weeks and very long term rehabilitation is likely.

McDonald said the situation was very traumatic.

“We have some very traumatised families and children in our hospital at the moment,” she said.

“We’re working extremely hard to provide that trauma support and care that they will need not just now but in the coming weeks and months.”

Detective Senior Sergeant Paul Lineham said the truck driver was taken into custody.

“That scene there was absolutely horrific,” he said.

“As a parent of a primary school-aged child myself, I can only imagine the absolute paralysing feeling that those parents had when they were first notified this bus rolled over.”

Lifeline 13 11 14

Kids Helpline 1800 55 1800 (for people aged 5 to 25)