Police have issued a public warning after a woman was sexually assaulted after getting off a bus in South Vancouver on Sunday.

The 20-year-old woman disembarked at Victoria Drive and East 64th Avenue just after 10 p.m. As she started walking west down East 64th, police said a man grabbed her from behind, told her he had a weapon and starting making sexual comments.

In a statement, police said he groped her repeatedly before suddenly letting go and running away towards Victoria Drive.

The suspect is described as Asian, five feet nine inches tall and 160 pounds with short black hair. Police said he was wearing a dark jacket, shorts and a medical mask over his face.

This is the second warning to the public about sexual assaults on women in as many days.

On Wednesday, police said a woman had been attacked in Yaletown just after 3 a.m. on Oct. 31.

According to police, that woman was approached by a man in his late 20s to early 30s who threw her to the ground and sexually assaulted her. He was interrupted by a passing driver who pulled over, even though, police said, the motorist was unsure what was happening.

The suspect ran eastbound on Expo Boulevard. He's described as having short black hair and a medium build, wearing a black hoodie and dark coloured backpack.

Vancouver Police Const. Jason Doucette said investigators are still working to determine if the incidents are related.

"We are open to all possibilites," he said Thursday. "We are asking anyone who may have been in the area at the time of the assault, and may have seen our suspect in the area, to call police."

Anyone who was near Victoria Drive and East 64th Avenue on Sunday at 10 p.m., or anyone who was in the area of Cambie Street and Expo Boulevard on Tuesday at 3 a.m. is asked to call the Sex Crimes Unit at (604) 717-0604.