The Porsche driver who allegedly fled the scene of a crash on a Melbourne freeway where four police officers were killed has been charged.

The driver was yesterday identified as 41-year-old mortgage broker Richard Pusey after he turned himself into police.

Mr Pusey was allegedly intercepted on the Eastern Freeway near the Chandler Highway just after 5.30pm on Wednesday.

First pictures of Porsche driver Richard Pusey in police custody. (Nine)

The Flinders Street Station is lit up in blue in tribute to the four police officers that died after being hit by a truck on Melbourne's Eastern Freeway. (AAP Image/Michael Dodge)

Four officers were at the scene when a semi-trailer crashed into them, killing the two senior constables and two constables. Mr Pusey allegedly took photos and videos of the scene before he fled on foot, with police saying the footage and images were later uploaded to social media.

Last night Victoria Police said Mr Pusey had been charged with driving dangerously, reckless conduct endangering life, fail to remain after a drug test, fail to render assistance, fail to exchange detail, possessing drug of dependence, destruction of evidence, and three counts of commit indictable offence while on bail.

He was remanded in custody to appear at Melbourne Magistrates' Court today.

Victoria Police Deputy Commissioner Shane Patton said further charges could be laid over the man allegedly taking photos of the crash which were then uploaded onto Facebook.

"We're still exploring whether there are offences committed under the Telecommunications Act," he told Nine's Today show on Friday.

It's not clear if the post or the dissemination of photographs was done by the man himself or by others.

The truck driver has been admitted to hospital where he is expected to remain for a number of days.

READ MORE: Officer bodycams to be used to piece together crash

READ MORE: Fallen police officers named as city mourns its heroes

Police arrested Pusey today. (Nine)

Mr Pusey is currently out on bail for previous charges. (AAP)

There has been an outpouring of grief for the four officers killed , Leading Senior Constable Lynette Taylor, Constable Glen Humphris, Senior Constable Kevin King and Constable Josh Prestney.

Last night Victoria Police Chief Commissioner Graham Ashton said footage from bodycams worn by the officers and cameras on the freeway would be used to piece together what led to the tragedy.

"I'm told that is quite illustrative," Mr Ashton told A Current Affair .

"We've got a lot of evidence to piece together and while we currently don't know [what caused the crash], we will know before too much longer."

READ MORE: Dashcam footage emerges of Porsche speeding down freeway

Mr Pusey outside his home. (AAP)

Richard Pusey featured on A Current Affair in 2016. (Nine)

It was earlier reported that Mr Pusey had allegedly been clocked driving at more than 140km/h.

He then allegedly tested positive to "some type of drug".

READ MORE: How the deadly Melbourne freeway tragedy unfolded

Richard Pusey, the driver of a Porsche who allegedly fled the scene of a truck crash on Melbourne's Eastern Freeway which killed four police officers, is taken away from his Fitzroy property by police. (AAP)

Richard Pusey is in police custody. (Nine)

A major investigation is underway. (9News)

The truck's driver has been named as Mohinder Singh Bajwa. He suffered a medical episode immediately after the crash and remains under police guard in hospital.

"The truck itself appears to have moved from one of the traffic lanes in the freeway into the emergency lane and has travelled a short distance in the emergency lane at around about 100km/h and has then slammed into the rear of the Highway Patrol vehicle," Mr Ashton said.

Truck driver Mohinder Singh Bajwa. (Facebook)

Victorian state coroner, Judge John Cain, and coroner Darren Bracken attended the collision site last night to commence a coronial investigation.

The tragedy was a timely reminder of the dangerous reality of being a police officer, Mr Ashton added.

A crushed police car leaves the crash site. (AAP)

Map of the crash site. (9News)

"It was a tragic day for obviously the families of these officers and we feel very deeply for them," Mr Ashton said.

"The whole force is reeling this morning from what's occurred last night. It's an unprecedented event for us to lose so many officers in one event, in one very terrible collision on the freeway.

"And officers just doing their work, doing their job, doing a duty that is performed by officers many times a day across our state.

"And it is just a timely reminder of how tragic police work can be at times, and indeed, very unexpectedly at times."

Emergency services clearing the crash site. (AAP)

It is the single deadliest incident in Victoria Police history.

Prime Minister Scott Morrison said today was "a terribly dark day" for Victoria Police.

"It is a dreadful and terrible reminder of the dangers that you face every single day," Mr Morrison said.

"You step up every day, you stand between us and that danger every single day and we are deeply grateful for your service, deeply grateful for your sacrifice and to those families who are knowing nothing other than terrible grief today, we stand with you as much as we possibly can."

An investigation by the Homicide Squad and Major Collision Unit remains underway.

The section of the Eastern Freeway reopened on Thursday about 4pm after more than 10 hours of investigating and wreckage removal.

Victorian Police Chief Commissioner Graham Ashton gives an update on the horror crash that claimed the lives of four police officers in Melbourne. (Nine News)

Police 'numb' after death of colleagues

Police Association Victoria secretary Wayne Gatt paid tribute to the officers, saying the tragedy was "incredibly sad" for everyone involved.

"I think the police force is waking up feeling numb, the members, the men and women of Victoria Police challenged deeply by this," Mr Gatt told Today this morning.

"We are hurting for the families that we know are obviously shocked and in immense pain overall.

"When something like this happens in policing it does send shockwaves around the force. It is one big family and that family transcends borders across the county, across the country and around the world.

"We have had members overnight obviously involved in assisting family and delivering those horrible messages.

"It's just floored us. To lose any member, but to lose four on one occasion is incredible and this will be felt in every police station, in every watch house across the state."

Victoria Police Deputy Commissioner Shane Patton lays a tribute at Boroondara Police Station. (AAP)

Premier Daniel Andrews led tributes to the female senior constable, male senior constable, and two male constables, who he labelled "heroes".

"Tonight, somewhere in our city, four families' hearts are breaking. Our hearts are breaking with them," Mr Andrews said.

Mr Andrews said an investigation would determine "why — how — this could possibly have happened".

"But one thing is already clear ... we will always call them heroes."

Victoria Police Minister Lisa Neville said there were plans to fly flags half-mast at parliament.

"There are really no words that you can adequately use tonight to express what has happened. It is an unimaginable tragedy," she said.