Truck Driver 'Very Much The Focus' Of Investigation Into Crash That Killed Four Police

The driver who was behind the wheel of a truck which killed four Victoria Police officers is at the centre of an investigation into the crash, but may not be interviewed for several days. 

Police believe Mohinder Singh, 47, was driving a refrigerated truck on the Eastern Freeway when it veered into the emergency lane at 100 km/h on Wednesday evening.

The truck struck and killed four police officers -- Leading Senior Constable Lynette Taylor, Senior Constable Kevin King and Constables Glen Humphris and Josh Prestney -- who had pulled over a black Porsche for allegedly speeding.

The Porsche driver, 41-year-old Richard Pusey, appeared in Melbourne Magistrate's court on Friday morning charged with 10 offences over the fatal crash.

But Deputy Police Commissioner Shane Patton said despite the interest in Pusey, the investigation into the crash is centred around the truck driver.

"There’s been a lot of focus on the male who allegedly ran away from the scene, but for us the focus is very much so on the driver of this truck," he told Neil Mitchell on 3AW.

Singh remains in hospital under police guard after suffering a medical episode at the scene of the crash, and police are yet to interview him.

Patton said on Friday morning the driver is currently "unfit to be interviewed".

He said the homicide squad and the major crash investigation unit is jointly approaching the investigation with a "fully open mind", but that Singh was "a [person of interest] for serious offences at this stage", including culpable driving resulting in the deaths of four people.

"It's an open investigation, we don't know what has caused the truck to crash," Patton said.

"We haven't ruled anything out at this stage, and pivotal to that is obviously speaking to the truck driver."

The driver remains under police guard in hospital, and officers hope to speak with him in the next couple of days.

On Wednesday night, police raided the truck driver's home at Cranbourne in the city's south-east, but are yet to reveal what was found.

10 daily has contacted Shane Patton for more information.

Anyone who was driving in the area who has dashcam footage or who witnessed the incident are being urged to contact CrimeStoppers.