Four Australian police officers killed in accident involving Indian-origin truck driver

Four Australian police officers were killed in the line of duty when a speeding Indian-origin driver ploughed his truck into them here after he apparently suffered a "medical episode," police said.

The truck driver Mohinder Singh Bajwa from Cranbourne suburb, on Wednesday veered into the emergency lane from one of the freeway lanes and travelled a short distance at around 100 km per hour where the four police officers were standing, said the police chief for the state of Victoria.

Victorian Chief Commissioner Graham Ashton said two of the officers had pulled a speeding Porsche car over in the emergency stopping lane when they decided to impound the vehicle and had called for two more officers to assist them.

The four police officers were out of their cars when the truck drove into the officers and the Porsche.

The truck slammed into the back of one the two police cars and hit the other police car and the Porsche before coming to a stop.

The Porsche was driven by a 41-year-old driver Richard Pusey who later fled the scene on foot and has been accused of taking pictures of the crash and posting them on social media. Pusey was currently in police custody after he was arrested on Thursday.

Flags are flying at half-mast across the state in honour of one female officer, and three male officers, one of whom only started work on Tuesday.

''As a chief commissioner, to have four officers killed last night - someone who has clearly been driving erratically on the freeway with an extensive criminal history, it disgusts me," Ashton said, adding "And then to leave the scene is a very, very low act in my view."