Fire crews were called Winnipeg Street and Eighth Avenue just before 10:00pm on Tuesday May 2nd.
The majority of the fire was contained to the west side of the the former General Motors plant, which was built in 1928 and taken over by the city in the 1960s.
It currently houses Hockey Regina, Regina Ringette, Regina Education and Action on Child Hunger, the Grid Virtual Reality Arcade and other businesses and organizations. There were also a number of semis, bobcats, and other large machines housed in the building.
Fire officials haven't released any other details about the blaze, but loud bangs were heard outside the building as the fire burned.
The cause of the fire and the extent of the damage are still unknown. No injuries have been reported.