Police are investigating after a fight outside a downtown Vancouver nightclub turned deadly this week.

Two men were arguing outside Shenanigans on Robson Street around 1 a.m. Tuesday morning when one of them threw a punch and knocked the other to the ground, according to police.

The victim, a 60-year-old local, suffered what was initially believed to be a minor head injury. He was taken to hospital, but refused treatment and left.

Shortly after, paramedics were called to a West End apartment building, where the man was found unresponsive on the floor.

He was returned to hospital, and it was determined he had suffered serious brain bleed. He died Wednesday morning.

Investigators are now trying to track down a person of interest who was caught on surveillance footage. He’s described as a white man in his 20s, 5-10 tall with a heavy build who was wearing a backwards baseball cap and a button-up shirt.

Anyone with information on his identity is asked to call police at 604-717-2500, or Crime Stoppers at 1-800-222-8477 to remain anonymous.