A working smoke alarm likely saved the lives of four tenants in an early morning house fire in North Bay. The alarm went off just before 8:00am Wednesday waking the sleeping occupants who got out of the home with only the clothing on their backs. Deputy Fire Chief Greg Saunders says the fire was so intense it blew out the main floor windows of the bungalow. Saunders says crews had the flames out in short order and limited the damage. An investigation into the cause is underway and no damage estimate is yet available. As for the tenants, they were sent to hospital for smoke inhalation. Saunders says it could have been worse for them had the smoke alarm not awoken them.