Police are looking for witnesses after a man was seriously injured outside a busy SkyTrain station in downtown Vancouver last week. 

Authorities said the 47-year-old victim was involved in an "altercation" with another man on Melville Street on the evening of March 20.

The suspect allegedly attacked him with a weapon before fleeing the scene, and the victim took a taxi to hospital for emergency treatment. Police did not disclose what weapon was used in the attack.

The assault took place just outside the bustling Burrard SkyTrain Station at around 7:30 p.m. Given how many people are constantly coming and going from the area, Const. Jason Doucette said police are hoping to speak with anyone who witnessed the attack – including possible Good Samaritans.

"We understand a couple of people may have tried to assist, and we'd like to hear from them," Doucette said in a news release.

Police haven't said what led up to the altercation, but confirmed the two men involved know each other.

Anyone who witnessed the incident is asked to call the Vancouver Police Department's Major Crime Section at 604-717-2500, or Crime Stoppers at 1-800-222-8477.