The service says in a release that police, firefighters and paramedics responded Thursday afternoon and fire officials say they received numerous emergency calls reporting large flames and heavy black smoke.
Ottawa Fire Services says two people are in critical condition and one has minor injuries.
Officials say a family reunification centre has been set up at the Woodvale Pentecostal Church to ensure everyone who was working at the business is accounted for.
Police say emergency crews continue to search the site and monitor the scene for flare-ups.
The Ontario Fire Marshal’s office is investigating.