The Porsche driver who allegedly fled the scene of a horror crash that killed four police officers has been named as Melbourne mortgage broker Richard Pusey.

The officers – one only a recent recruit to Victoria Police – died when they were hit by a semi-trailer after pulling over the Porsche 911 for speeding about 5.30pm on Wednesday.

On Thursday afternoon, Victoria Police named the group as Leading Senior Constable Lynette Taylor, Constable Glen Humphris, Senior Constable Kevin King and Constable Josh Prestney.

“Their names will forever be remembered, their service honoured, and their memories celebrated,” Chief Commissioner Graham Ashton said.

“These officers were undertaking their everyday duties in helping to keep the community safe when they were killed.”

Earlier, devastated senior police alleged Mr Pusey, 41, was travelling at 140km/h when he was stopped by Leading Senior Constable Taylor and Constable Humphris on the Eastern Freeway at Kew, in inner-Melbourne.

• Who is Richard Pusey? Read more here

Constable Josh Prestney was one of the four officers killed. Photo: Facebook

The first two police officers called for back-up from Senior Constable King and Constable Prestney to impound the Porsche.

All four were talking to Mr Pusey in the freeway’s emergency lane when a refrigerated truck ploughed into them. They died at the scene.

Police also allege Mr Pusey took photos of the crash scene and uploaded them to social media, before fleeing. He was not found until Thursday morning.

He remained in police custody on Thursday afternoon, and was yet to be charged.

Mr Ashton urged people not to share the photos.

“There have been some images placed on Facebook that appear to have been taken by this individual at the scene, before he has left the scene,” he said.

“Some of those photographs were circulating last night online.

“We are talking to Facebook this morning about removing them.”

Mr Ashton said the semi-trailer was travelling at 100km/h and hit one police vehicle so hard it spun across the lanes of the freeway, coming to a stop in the nature strip between the inbound and outbound lanes.

The truck driver, whose injuries are not life-threatening, remains in hospital under police guard. Police have searched his home in outer Melbourne, and hoped to interview him on Thursday.

Mr Ashton said the truck driver suffered a medical episode after the crash, “which seemed to involve him blacking out”.

Tweet from @VictoriaPolice

The deaths of the two senior constables and two constables is Victoria Police’s worst loss of life since three officers died in a shootout with Ned Kelly in 1880.

Flags were flying at half-mast across Victoria on Thursday in honour of the group.

“The whole force is reeling this morning, from the events of last night,” Mr Ashton said.

Trevor, a cousin of one of the dead officers and who drives a truck similar to the one in the crash, told Melbourne radio 3AW he was shocked by the tragedy.

“It hasn’t hit home yet, but the job they do, I don’t think is respected enough,” he said.

Tweet from @DanielAndrewsMP

Tweet from @SAPoliceNews

Tweet from @ScottMorrisonMP

Police Association Victoria secretary Wayne Gatt said he hoped “we never have another day like this”.

“Make no mistake, whilst this incident occurred in the eastern suburbs of Melbourne, the ripple effect was within minutes felt in far-flung regions of the state,” he said.

Premier Daniel Andrews asked all Victorians to pause and honour Victoria Police officers for their work.

“To live a life in the service of others is a deeply impressive thing. To lose your life in the service and protection of others is a tragedy,” Mr Andrews.

Prime Minister Scott Morrison said the tragedy was a reminder of “the dangers that you face every single day.”

“You step up every day, you stand between us and that danger every single day and we are deeply grateful for your service.”

More than $37,000 has been raised towards the $2 million target for the families of the deceased police officers via a GoFundMe page.

The freeway remained closed for several kilometres in both directions on Thursday afternoon. Police asked motorists to avoid the area.

-with agencies