A firefighter lost part of a finger while helping to battle a two-alarm fire on Milwaukee's north side, officials said. The fire was reported late Monday night at a duplex near 4th Street and Concordia Avenue. Flames then spread to a neighboring duplex. Police told WISN 12 News the firefighter was injured while using a saw on the roof. The firefighter was taken to the hospital to be treated. No one else was hurt. A total of 19 people from four families were displaced because of the fire, according to a volunteer with the Red Cross. The cause of the fire was unknown as of 7:30 a.m. Tuesday.