Driver of car in Melbourne attack undergoes surgery

A man shot by Australian police on Friday will be questioned once he emerges from surgery, police said on Saturday, a day after the 26-year-old drove a car into pedestrians in a crowded Melbourne street, killing four, and injuring more than 20.

Police have said the incident was not terrorism related, dispelling initial fears that it might have been an attack by an Islamist militant.

The man was shot after police rammed his car, before dragging him from the vehicle.

The bullet wound to the arm was not life threatening, but needed surgery, Victorian police commissioner Graham Ashton told reporters in Melbourne on Saturday.

"That surgery is still occurring," Ashton said. "Through the course of the weekend we will be looking to try and get that opportunity to step in and interview and charge that offender."

A 10-year-old girl was among the dead, but police said the death toll could rise as a baby and four others were very seriously hurt.

Ashton said the incident was not terrorism related, and that the driver had a "criminal history" that included domestic violence charges laid a week earlier for which he was already on bail.

Victorian Premier Daniel Andrews said a memorial would be built to the victims in the Bourke St mall where they died. He joined dozens of others in laying flowers at a makeshift shrine on the footpath there.