Fire crews are working to put out a two-alarm fire at an abandoned building on Wellington Street West in downtown Toronto.

Crews were called to the scene near Front Street West and Spadina Avenue just after 11:30 a.m. Monday for reports that smoke was seen coming out of the boarded-up building.

Toronto police reported smoke billowing from the roof of the building, and that a small explosion was heard.

Smoke can be seen coming from the abandoned building on Wellington Street West. (Mathieu Simard/Radio-Canada)

Toronto Fire Capt. David Eckerman told CBC Toronto that when firefighters arrived, explosions could be heard coming from the building.

Eckerman said there were unconfirmed reports of a person inside working. Fire crews will be doing a search of the building.

Police have blocked roads in the area.