A fire that consumed several row houses in Toronto's Kensington Market earlier this week was deliberately set.

Const. David Hopkinson told CTV Toronto Wednesday that the Fire Marshal's Office has completed their investigation. He said police have launched an arson investigation in connection with the four-alarm blaze.

On Monday, more than 100 firefighters and 20 trucks were called to the neighbourhood after a fire started on the deck of one of the homes on Oxford Street. The blaze started at approximately 1 a.m., and quickly spread to nearby homes. It was mostly extinguished by 3:30 a.m.

Firefighters previously said the estimated damage to the homes, located at 10, 12, 14 and 16 Oxford St. is approximately $1 million.

No one was injured, but five cats that belonged to a retired couple died in the fire.

A Toronto Fire division commander told reporters at the scene on Monday that there have been suspicious fires nearby recently, including one in a garage on Augusta Avenue.