A fire of undetermined origin yesterday afternoon caused substantial damage to an apartment unit and to the roof of a complex at 314 Riverview Drive in Manitowoc.  A second floor tenant was rescued by Manitowoc firefighting personnel…after she attempted to find her pet in the flames.  The woman was treated at the scene and then transported to a local hospital for further evaluation.  There’s smoke & water damage to the rest of the 16-unit occupancy.  A damage estimate is unknown and the cause of the fire, discovered just before 4:00 o’clock, is still under investigation.  The Salvation Army and Red Cross are providing assistance.