Mount Vernon N.Y.- 5 firefighters were injured while battling a 3 alarm structure fire on the citys south side.heavy fire conditions were encounted upon arrival of the 1st due companys. The 3 story structure recieved heavy damage and displaced 5 families who were left homeless. Mt Vernon firefighters continue the battle with city officials including the fire chief and fire commisioner over shortage of manpower.The 1730 hr blaze was extinguished by 2000 hrs. Members of the Yonkers N.Y.F.D provided coverage for the city while Mt Vernon firefighters were committed to the scene.All injuries were minor to the firefighters.Residents of the builing made several complaints over the past year about poor conditions of the building prior to the fire.