Tributes to the four police officers killed in a highway crash in Melbourne this week have been flooding social media as the city turned blue in their honour.

A Melbourne boy pays tribute to the four fallen officers in a police uniform outside his house. Source: Facebook
The four officers killed in the crash have since been named as .

A woman lays a tribute at Boroondara Police Station near the Chandler Highway in the suburb of Kew. Source: AAP
On Thursday evening, landmarks including Flinders Street Station, Federation Square and the Melbourne Cricket Ground were lit up in blue to pay tribute to the fallen officers.
Meanwhile, residents placed blue ribbons on their front doors and laid flowers at the Boroondara Police Station in Kew, the suburb where the incident occurred.
The four officers were dealing with a speeding Porsche driver who had just tested positive for drugs when a refrigerated truck veered into the emergency lane and killed them.
Two of the four officers killed were trainees.