A German backpacker has died after what Queensland police described as an incident of road rage that led to him being stabbed in inner-city Brisbane early on Friday morning.

Police say the man, aged in his early 30s, was crossing Milton Road in Petrie Terrace with a friend about 4:00am when they were hit, or nearly hit, by a car travelling toward the CBD.

The German backpacker got into an argument with the male driver.

A female passenger was also believed to be in the car at the time.

The backpacker was stabbed in the back and stomach with an unknown object, and had to be resuscitated at the scene by paramedics.

He was taken to the Royal Brisbane and Women's Hospital in a critical condition but later died.

It is believed the man and his friend were staying at a nearby backpacker hostel.

Inspector Daniel Bragg said "it may have been a road rage-type situation".

"The two men were on their way back home after a night out and they were crossing the road when this altercation with the driver of the vehicle ensued," he said.

"The vehicle, we're led to believe, may have struck or come close to striking a male who was endeavouring to cross the road at the time.

"This developed into a physical altercation on the street, the consequence of which the male victim sustained some serious injuries."

Homicide investigation centre set up

An investigation centre was established in the inner city on Friday, with the police now investigating the incident as a homicide.

A number of vehicles have come to their attention, with a green Barina being noted as a vehicle of interest.

Inspector Daniel Bragg at the scene of the stabbing on Milton Road. ( ABC News )

Detective Superintendent Tony Fleming described the incident as a "tragedy".

"There's a family on the other side of the world who will be getting news that someone they love left home and is not coming home the way they expected them to," he said on Friday.

"Whatever caused that incident today [on Friday], the person involved would appear to have done something that is entirely unacceptable in our society.

"A young man has lost his life and I'm sure no-one woke up this morning or finished their night last night thinking that they would be involved in an altercation that would result in this."

Police are urging the man and woman from the car to come forward.

"We would ask that they would think about what's happened and certainly that we would ask that they contact the police or attend a police station so we can hear their side of the story," he said.

"To the gentleman involved we would ask, we're not going to stop looking so we would ask that you make yourself known to us."

Police have spoken to a number of witnesses but said they would like to hear from anyone with dashcam footage or the registration number of the vehicle.