North Bay fire crews quickly knocked down what’s described as a “substantial” house fire this morning (Wednesday) on Cartier Street.

Deputy Fire Chief Greg Saunders says the house was fully involved when they arrived on the scene.

“The fire had already vented itself, which means it had already blown out the windows, it was a substantial house fire,” he says.

Four people got out of the home with only the clothes they wore to bed and called 911.

Officials say they were taken to hospital for observation, possibly for smoke inhalation.

As for the investigation, it’s just getting started.

“Fire prevention will be in, it’s too early to tell cause yet,” Saunders says.

All three fire stations responded to the blaze on the 400 block of Cartier Street, just before 8 o’clock this morning.