A three-alarm fire that destroyed a Roots store on Queen Street West was caused by arson, authorities have told CityNews.

The fire erupted around 1 a.m. on Tuesday and was put out around 1:30 a.m. Firefighters battled minor flareups as late as 2:15 a.m.

Toronto Fire confirmed the roof of the building caved in while a portion of the front collapsed.

Fire fighters conducted a search and did not find anyone in the building, which is located on Queen at Soho Street, west of Spadina. The building housed the Roots store on the ground floor and apartments above.

No injuries were reported.

Police are unsure how the fire started but had originally said that strong winds and severe rain due to superstorm Sandy were factors.