Senior Sergeant Paul Hargreaves of Warrnambool police said people should be patient as officers continue to sift through the evidence left behind and work out what, if anything, should be done next.

"There are a number of things we have to go through - the mechanical aspects of the motor vehicles and other evidence we gather at the scene needs to be collated and worked through," Senior Sergeant Hargreaves said.

"It can take sometimes weeks, sometimes months."

Meanwhile, two of the children on the school bus - Emily Blake and Jake Croft - remained in a critical condition overnight at the Royal Children's Hospital, while fellow pupil Kaytlyn Wallace was in a stable condition.

It is understood one of the children was undergoing an operation on their hand today.

The 64-year-old bus driver from Nullawarre remains in a stable condition at the Royal Melbourne Hospital.

It has also come to light that a Moyne Shire Council road crew was among the first on the scene of the accident and provided valuable assistance in the vital moments after the crash.

Shire chief executive officer Brett Stonestreet said one employee was at the accident shortly after it happened and contacted others.

He said the workers sat with the children until the ambulances arrived, making sure the kids were comfortable and not alone.

"We're very proud of our staff," Mr Stonestreet said.

"A number of staff (attended) the scene after this terrible accident and stayed there for many hours . . . and assisted where they could."

Mr Stonestreet said Moyne Shire was offering the employees all the support they needed.

"They were quite shaken up by the whole thing, especially because there were children involved,'' Mr Stonestreet said

"We'll be touching base with (the staff members) over the weekend (because often it) doesn't really hit the system until later.