The fires were centred around Macdonell Avenue in the Parkdale neighbourhood, CBC's Trevor Dunn reported from the scene. One fire was on Garden Avenue.
The fires melted trash bins along the street, but caused no damage to homes and no apparent injuries. It was garbage day in the area and the bins were near the street.
Police are interviewing potential witnesses and said one man may have been seen pouring a liquid on the bins and fleeing the scene on a bicycle. No description has yet been released.