This BBC report http://www.bbc.co.uk/news/world-australia-38685972 is interesting for several reasons, firstly for the headline blaming the driver not the vehicle as they did in Nice and Berlin. Secondly for the explanation of the police's view that immediately follows the initial description of the incident:
'Three people, including a young child, have died after a car deliberately hit pedestrians in central Melbourne, police say.
At least 29 people were injured, among them a baby who is in a critical condition after the car hit a pram.
Police say they rammed the car, shot the driver in the arm and arrested him.
They say the incident was not terror-related, but is believed to be linked to a stabbing in Melbourne's south-east early on Friday.'
So NOT terror related. It may well not be but I note that PJ Media are reporting a different line based upon at least one witness.