An early morning fire displaced at least a dozen people and left one woman with trouble breathing today in Waianae. 

The fire, which was reported at 4:07 a.m., heavily damaged at least two units and caused smoke damage to other units in a townhouse structure on Ala Walua Street, said Honolulu Fire Department spokesman Capt. David Jenkins. The two-story structure has at least six units. 

More than 30 firefighters from 10 companies responded and found several units engulfed in fire. Firefighters brought the blaze under control at 5:08 a.m. 

About an hour later, a 40-year-old woman was treated by firefighters and an Emergency Medical Services crew because she was having difficulty breathing, firefighters said. 

Red Cross was summoned to help two families consisting of at least a dozen people who were displaced. 

The cause of the fire was under investigation, and a damage estimate was undetermined.