Police officers were called to the Jazz building on Church Street, between Shuter Street and Queen Street East, at around 4:20 p.m. after the man allegedly smashed several windows.
Police say the man then ran into the apartment building, where he appeared to have barricaded himself in an apartment.
Police reopened Church Street around 6 p.m. after dealing with the man. A CBC reporter on scene said it's possible the man may have been apprehended and taken out the back of the building.
Police have yet to announce if the man will face any charges.
Photos shared on Twitter show a young man holding up an apparent knife on his patio.
An ETF team was also photographed on a nearby balcony.
Nobody was injured.