More than two dozen people were forced to evacuate their homes near Albion Mall following reports of toxic gas levels in the sewers.
Police said they received a call from fire officials just before 3 p.m. about the smell of gas on Bulbourne Road near Albion Road and Finch Avenue West.
Upon arriving, police were advised by Toronto Fire that as many as eight homes in the area needed to be evacuated as a precaution due to toxic levels of gas in the sewers.
Toronto Fire said it did not appear to be a gas leak but rather some sort of solvent dumped into the sewer system which created the potentially explosive gas readings.
TTC buses were brought in to temporarily shelter those evacuated as officials flushed the sewer system.
Residents were allowed to return to their homes later in the evening.