Police say the fire started on Friday morning at about 6:00, as the bus reached Broad and Ruscomb streets in the Logan section of the city.
The driver and passengers managed to get out of the bus quickly.
One person suffered smoke inhalation.
He has been taken to the hospital, and is in stable condition.
Traffic delays remain in the area, while police continue their investigation.
There's no word yet on what caused the fire, or on how many passengers were on the bus.
