A man with a shopping trolley has been praised for trying to subdue a knife-wielding attacker who had just stabbed three people in Melbourne.
People are at the scene of a major operation in Bourke St in the CBD after a vehicle crashed and exploded about 4.20pm.
The driver then got out and began stabbing pedestrians in a terrifying frenzy, injuring two and killing one, police say.
Video shows the dramatic moment the attacker lunges at two responding police officers with the knife.
Simultaneously, one heroic eyewitness rushes at the attacker with a shopping trolley, briefly slowing him down and falling in the process.