Vancouver police are hunting for a man they believe sexually assaulted a 25-year-old woman after she got into what she thought was a taxi in Gastown Saturday morning.

The North Vancouver woman flagged down an older model, dark minivan with sliding doors on both sides, thinking it was a cab, in the 100 block of Water near Abbott Street, at around 2 a.m. PT.

The driver then took the woman, who has not been identified, to an area in East Vancouver, where she was beaten and sexually attacked, before she managed to escape and someone nearby called 911.

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Vancouver police Const. Brian Montague said a North Vancouver woman was violently assaulted after getting into what she thought was a cab in Vancouver's Gastown area Saturday morning. (CBC)

Const. Brian Montague said investigators are working around the clock to track the suspect down.

"We've spent quite some time with the victim and she's very traumatized," said Montague.

The suspect is described as an Aboriginal man, aged between 35 and 39 years old, heavy set with a fat belly

He weighs about 250 pounds, is around six feet tall and has a shaved head.

Anyone with any information about the attack or the suspect is asked to call the Vancouver Police Sex Crimes Unit at 604-717-0602 or to remain anonymous, Crime Stoppers at 1-800-222-8477.

With files from the CBC's Farrah Merali