A man in Gastown was rushed to hospital with serious burns on over 40 per cent of his body after catching on fire while overdosing on drugs.

Crews discovered the injured man after being called to deal with a fire on a balcony in Blood Alley during the supper hour on Wednesday.

Police say he had overdosed and somehow caught on fire from a lit candle.

Adam Parsons, who was working in a restaurant across the street, grabbed a fire extinguisher and rushed to help.

"Ran up there and called 911 and put the guy out on fire and put the fire on the corner out as well and yeah it was pretty crazy," he told CTV Vancouver.