Four Australian police officers killed by truck after stopping speeding Porsche driver

(Scott Barbour/AAP Image via AP)

A truck has killed four police officers who had detained a drug-affected speeding driver on an Australian motorway, officials said.

The 41-year-old driver of a Porsche 911 who had been pulled over for speeding by officers on the Eastern Freeway in Melbourne took grisly photos of the crash scene that followed, Victoria Police Chief Commissioner Graham Ashton said.

The driver then fled on foot and posted the images online, Mr Ashton said.

The tragedy was the largest loss of police lives in a single incident in Victoria state, he said.

The refrigerated truck driver was under police guard in hospital. He suffered a medical episode after the crash and had lost consciousness, Mr Ashton said.

It was not clear whether the collision was an accident or deliberate, the police chief added.

The Porsche driver, who has a criminal record, was in police custody and was being questioned by homicide detectives, Mr Ashton said.

He had been pulled over 50 minutes before the crash for driving at 25mph above the speed limit, police said. He then tested positive for an illicit drug.

The officers were in an emergency stopping lane arranging to impound the car when they were struck.

The truck hit the back of a police car, spinning it out of the lane, before crashing into the Porsche, which became wedged under the cabin.

All the officers present – three men and woman – died at the scene.