The Windsor Police Arson Unit is looking into another intentionally set fire, this time on Frank Avenue.
Friday's fire between Wyandotte Street East and St. Rose Avenue displaced two people and caused up to $100,000 in damage.
Mike Coste, a fire prevention officer with Windsor Fire and Rescue Services, said someone used an incendiary liquid to start the fire.
Windsor Police confirmed its investigation on Tuesday morning.
The blaze is the sixth intentionally set fire this month.
Two investigations, on Baseline Road and at an East Windsor department store, resulted in charges against two suspects. The fires are unrelated.
Police are also investigating after three homes under construction on Cowan Court in Amherstburg were recently set ablaze, causing $4-million in damage.
Another fire on Tuesday morning on Drouillard Road started in an overheated dryer and caused minimal damage. It is not considered suspicious.