Police are appealing for the driver of a dark sedan to come forward following a hit-and-run that resulted in the death of a 20 year old in Toowong.

Ashleigh Humphrys is believed to have been celebrating her 20th birthday in Toowong when she was killed by a dark sedan while walking near the Western Freeway roundabout at approximately 3:50am on Sunday.

An off-duty security guard attempted to assist the woman when he spotted her walking and notified police, fearing for her safety, but it was too late.

Inspector Rob Graham is urging the driver to come forward, and has CCTV footage of two taxis parked near the woman with their hazard lights on shortly before she was killed.

“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.”

Inspector Graham is calling on the driver to come forward and present their side of the story.

“We want to put pressure on the driver and let him know that we’ve got CCTV footage and our preference would be for him or her to come forward and give us the information.”

The vehicle is believed to have been heading towards the city at the time.

Police are also calling on the public to come forward if they recall a dark sedan being driven erratically in the area at that time, or noticed a car of the description with significant damage.

A taxi that was the first car on the scene of the fatal hit-and-run has been seized by police for inspection as a precaution.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.