A man is being treated in hospital after he knocked on a door in a Toronto apartment building Wednesday night and was attacked by a dog, Toronto police say.

"The person who lived there set the dog on him," Const. David Hopkinson told CBC News.

Hopkinson said police received a call from the victim at about 8:40 p.m. The incident occurred near Gower Street in the Dawes Road and Victoria Park Avenue area.

Police said the man was going door-to-door for a lawful reason, a resident answered when he knocked, and the resident released the dog. The dog was described as large, but there's no word on the breed.

Hopkinson said no one has been arrested but police are investigating.

He said the first priority of police is to ensure the victim is treated for his injuries. He declined to say how many times the victim was bitten.