Winnipeg police say they found a man on fire in this alley off the 500 block of Selkirk Avenue. ((CBC))

A 47-year-old man is in critical condition in hospital after he was attacked and set on fire, Winnipeg police say.

The assault happened around 11:30 p.m. CT Friday in a back alley off the 500 block of Selkirk Avenue.

Police said the victim's clothes and skin were on fire when officers arrived and they used a fire extinguisher to put out the flames.

Family members say the victim is Gerald Dumas, and Joyce Spilchuk, his aunt, told CBC News Saturday they are concerned he may not survive.

Spilchuk said her nephew is a gentle man with two children.

"I was devastated," Spilchuk said, upon learning what happened. "My nephew [is] a gentle giant. He doesn't touch or hurt anybody."

On Saturday morning police reported that a 19-year-old man was in custody in connection with the attack.