At 1230 hours Box 1-2 sent companies to 14 N. 18th Street for smoke in a structure. Squad 8 on location with nothing showing from a 3 story, occupied, duplex. Interior crews report smoke condition on the second floor. A line is stretched and Wagon 4 charged the hydrant. A fire involving the walls between the first and second floors at 16 N. 18th Street was quickly knocked down. Fans were set up and Chief 7 (Horst) marked control. Units on location: Squad 8 (using spare E2), Wagon 4 (using spare E6), Tower 1, Tower 3, and Chief 7.