Thunder Bay Fire Rescue says four people had to be taken to hospital following a blaze at an industrial complex on Neebing Avenue.
The first unit arrived around 10:40 and discovered smoke and flames.
All the occupants managed to get out of the building.
A second alarm was sounded, and fire crews were able to quickly extinguish the flames.
A total of six pumper trucks, one aerial ladder truck and a command unit responded.
The Ontario Fire Marshall’s Office and the Ministry of Labour are currently on the scene investigating the cause of the fire.
