One person was stabbed to death and two others wounded after they were attacked by a man in the centre of the Australian city of Melbourne on Friday, police said.
One witness said one of the stabbing victims, believed to be a man in his 60s who later died, was stabbed in the face, and that desperate efforts were made to save him. Some witnesses said the vehicle exploded before the man began stabbing people.
Witnesses called the stabbings "random", the ABC reports.
Social media users have shared photos and videos of the incident.
For further updates follow Victoria Police.
The officers ultimately fired a shot, causing the man to fall down.
Moments later, two plain clothing officers manage to get the offender to the ground, presumably after he was shot in the chest.
Commissioner Ashton said the man was known to police and the federal intelligence agencies.
Two others remain in hospital. Two are being treated for their injuries.
"Police shot the male and he is now in a critical condition and under guard in hospital".
It is not yet clear whether he deliberately set the vehicle on fire but Mr Ashton said it had been laden with gas cylinders.
The area has since been cordoned off by the bomb squad.
Islamic State - which often claims responsibility for such attacks - said via its propaganda arm that the perpetrator was an "Islamic State fighter and carried out the operation".
Police said there was no terrorism link at this stage but they are "keeping an open mind".
Police will investigate a possible copy-cat motive.
"Then I heard a loud bang and someone said they could see someone doing chest compressions on someone as an ambulance started coming up the street as well".
The Friday incident took place blocks away from Flinders Street Railway Station, where a driver plowed into pedestrians past year, injuring 18. In December, a different driver in Melbourne drove into more people, injuring at least 19.
Victorian Premier Daniel Andrews has praised both authorities and members of the public for their quick response in taking down the offender.
While opposition leader Bill Shorten tweeted, "when evil attacks our city, Melbourne stands together".