A young woman believed to have just celebrated her 20th birthday with a night out has been killed in a hit-and-run accident at Toowong in inner Brisbane.

Police said the woman had been celebrating on Saturday night and was hit while walking near the Western Freeway roundabout opposite Toowong Cemetery around 3:50am on Sunday.

Inspector Rob Graham said CCTV footage showed two taxis stopped near the woman shortly before she was killed.

"We want to put pressure on the driver [of the car involved]," he said.

"We want him to know that we've got CCTV footage.

"Our preference would be for him or her to come forward and give us the information.

"We're desperate to speak to the driver of a dark coloured sedan that passed the two cabs and continued driving on down towards Milton," he said.

"We're also desperate to talk to the two cab drivers."

Police believed the vehicle that struck the woman was heading towards the city.

They also want to hear from anyone who was in the area at that time who saw a car being driven erratically, or a car that had significant damage.

Inspector Graham said police received a phone call from a member of the public who said he had some concerns for the safety of a woman he had seen walking on Mount Coot-tha Road.

He said the caller told police the woman looked to be affected by alcohol or another substance "and she was either a danger to herself or other road users".

"While he's on the phone talking to police and driving around to try and determine her exact location he came across her deceased on the road.

"We are of the understanding that she was actually out in town last night celebrating her 20th birthday with her friends.

"She came back to an address in the vicinity of Mount Coot-tha Toowong and we understand that there may have been some verbal arguments there with her friends and she left that location."

Driver 'would have known she had been hit'

Earlier, Inspector Steve Flori said it was likely the driver knew the woman had been hit.

"Until we talk to the driver we won't be 100 per cent certain whether the driver knew, but because of the significance of the young woman's injuries it would be my belief that there is no mistake in the driver's mind that they have struck a person," he said.

"We're not in a position to know what that vehicle was, but what we are calling for is witnesses who may have been in that area at the time who may have any information that could lead us to identify the vehicle that actually struck this young woman."

Ambulance operations supervisor Matt McGregor said people always needed to stay at the scene of a serious accident to render first aid that could save a person's life.

"People can assist in many ways by staying on scene and helping us getting directed to the incident in our best possible response time," he said.

Inbound lanes of Milton Road were closed from Toowong for several hours but have since reopened.